You just write a recursive-descent parser. Doing that is pretty easy. Here's most of one:

#!/usr/bin/perl -w
use strict;

use Data::Dumper 'Dumper';

my %Data;

my $Comment =   '/[*]([^*]+|[*]+[^*/])*[*]/';
my $Name =      '([a-zA-Z_][a-zA-Z0-9_]*)';
my $Quoted =    '"([^"]*)"';


local $/;
my $code = <DATA>;
parse( \$code );
print Dumper( \%Data );
exit;

    sub parse {
        my( $svCode ) = @_;
        skip( $svCode );
        while( $$svCode !~ /\G\z/gc ) {
            if( $$svCode =~ /\Goptions(?!\w)/gc ) {
                parseOptions( $svCode );
            } elsif( $$svCode =~ /\Gobject(?!\w)/gc ) {
                parseObject( $svCode );
            } else {
                fail( $svCode, "Expected 'options' or 'object'" );
            }
            skip( $svCode );
        }
    }

    sub skip {
        my( $svCode ) = @_;
        0
            while   $$svCode =~ /\G\s+/gc
                ||  $$svCode =~ /\G$Comment/gc;
    }

    sub expect {
        my( $svCode, $re, $desc ) = @_;
        skip( $svCode );
        fail( $svCode, "Expected ", $desc )
            if  $$svCode !~ /\G$re/gc;
        my $return = $1;
        skip( $svCode );
        return $return;
    }

    sub fail {
        my( $svCode, @error ) = @_;
        my $pos = pos $$svCode;
        my $before = substr( $$svCode, 0, $pos );
        my $line = 1 + ( $before =~ tr/\n/\n/ );
        my $col = 1 + length( $before =~ /([^\n]*)\z/ ? $1 : '' );
        my $next = $$svCode =~ /\G([^\n]{1,8})/gc ? $1 : undef;
        die @error, " at line $line, col $col, before '$next'.\n"
            if  defined $next;
        my $after = $before =~ /([^\n]{1,8})\z/ ? $1 : undef;
        die @error, " at line $line, col $col, after '$after'.\n"
            if  defined $after;
        die @error, " at line $line, col $col.\n";
    }

    sub parseOptions {
        my( $svCode ) = @_;
        expect( $svCode, '[{]', "'{' after 'options'" );
        while( $$svCode !~ /\G[}]/gc ) {
            my $name = expect( $svCode, $Name, 'option name' );
            if( $$svCode =~ /\G$Name/gc ) {
                $Data{''}{$name} = $1;
            } elsif( $$svCode =~ /\G$Quoted/gc ) {
                # TODO: Unescape things that can be escaped inside quo
+tes
                $Data{''}{$name} = $1;
            } elsif( $$svCode =~ /\G[{]/gc ) {
                parseListOption( $svCode, $name );
            } elsif( $$svCode =~ /\G\z/gc ) {
                fail( $svCode, "Missing '}' at end of options" );
            } else {
                fail( $svCode, "Unsupported value for option '$name'" 
+);
            }
            expect( $svCode, ';', "';' after option '$name'" );
        }
        expect( $svCode, ';', "';' after options" );
    }

    sub parseListOption {
        my( $svCode, $name ) = @_;
        skip( $svCode );
        my @values;
        while( $$svCode !~ /\G[}]/gc ) {
            skip( $svCode );
            if( $$svCode =~ /\G$Name/gc ) {
                push @values, $1;
            } elsif( $$svCode =~ /\G$Quoted/gc ) {
                # TODO: Unescape things that can be escaped inside quo
+tes
                push @values, $1;
            } elsif( $$svCode =~ /\G\z/gc ) {
                fail( $svCode, "Missing '}' at end of list of option '
+$name'" );
            } else {
                fail( $svCode, "Unsupported value in list of option '$
+name'" );
            }
            expect( $svCode, ';', "';' after value in list of option '
+$name'" );
        }
        $Data{''}{$name} = \@values;
    }

    sub parseListObject {
        my( $svCode, $obj, $name ) = @_;
        skip( $svCode );
        my @values;
        while( $$svCode !~ /\G[}]/gc ) {
            skip( $svCode );
            if( $$svCode =~ /\G$Name/gc ) {
                push @values, $1;
            } elsif( $$svCode =~ /\G$Quoted/gc ) {
                # TODO: Unescape things that can be escaped inside quo
+tes
                push @values, $1;
            } elsif( $$svCode =~ /\G\z/gc ) {
                fail( $svCode, "Missing '}' at end of list '$obj'.'$na
+me'" );
            } else {
                fail( $svCode, "Unsupported value in list of '$obj'.'$
+name'" );
            }
            expect( $svCode, ';', "';' after value in list of '$obj'.'
+$name'" );
        }
        $Data{$obj}{$name} = \@values;
    }

    sub parseObject {
        my( $svCode ) = @_;
        my $obj = expect( $svCode, $Quoted, 'object name' );
        # TODO: Unescape things that can be escaped inside object name
+s
        expect( $svCode, 'in', "'in' after object '$obj'" );
        expect( $svCode, '[{]', "'{' for object '$obj'" );
        while( $$svCode !~ /\G[}]/gc ) {
            my $name = expect( $svCode, $Name, "option name for object
+ '$obj'" );
            if( $$svCode =~ /\G$Name/gc ) {
                $Data{$obj}{$name} = $1;
            } elsif( $$svCode =~ /\G$Quoted/gc ) {
                # TODO: Unescape things that can be escaped inside quo
+tes
                $Data{$obj}{$name} = $1;
            } elsif( $$svCode =~ /\G[{]/gc ) {
                parseListObject( $svCode, $obj, $name );
            } elsif( $$svCode =~ /\G\z/gc ) {
                fail( $svCode, "Missing '}' at end of object '$obj'" )
+;
            } else {
                fail( $svCode, "Unsupported value for '$obj'.'$name'" 
+);
            }
            expect( $svCode, ';', "';' after '$obj'.'$name'" );
        }
        expect( $svCode, ';', "';' after object '$obj'" );
    }

__END__
/* SOME COMMENT HERE */
/* MORE COMMENT */
/* Description - information */
options {
        option1 value;
        option2 value;
        option3 "value";
        option4 { value1; value2; };
};

/*
identifier1
 ID 123456
*/

object "identifier1" in {
        option1 value;
        option2 "value";
        option3 { value1; value2; };
        option4 { value; };

};

/*
identifier2
 ID 234561
*/

object "identifier2" in {
        option1 value;
        option2 "value";
        option3 { value1; value2; };
        option4 { value; };

};

/*
identifier3
 ID 345612
*/

object "identifier3" in {
        option1 value;
        option2 "value";
        option3 { value1; value2; };
        option4 { value; };

};

/* EOF */
[download]

And it even runs:

$VAR1 = {
    '' => {
        'option1' => 'value',
        'option2' => 'value',
        'option3' => 'value',
        'option4' => [ 'value1', 'value2' ],
    },
    'identifier1' => {
        'option1' => 'value',
        'option2' => 'value',
        'option3' => [ 'value1', 'value2' ],
        'option4' => [ 'value' ],
    },
    'identifier2' => {
        'option1' => 'value',
        'option2' => 'value',
        'option3' => [ 'value1', 'value2' ],
        'option4' => [ 'value' ],
    },
    'identifier3' => {
        'option1' => 'value',
        'option2' => 'value',
        'option3' => [ 'value1', 'value2' ],
        'option4' => [ 'value' ],
    },
};
[download]