#!/bin/sh
perl -I /some/special/libpath:/another/special/libpath "$@"
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Drop in an exec to get rid of a needless /bin/sh instance:

#!/bin/sh
exec perl -I /some/special/libpath:/another/special/libpath "$@"
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And if you have more than one perl, specify which one you want to start. Also do this if you are not sure what $ENV{'PATH'} may contain.

#!/bin/sh
exec /usr/local/perl-5.42.99/bin/perl -I /some/special/libpath:/anothe
+r/special/libpath "$@"
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But then again, cbeckley++ is right, perl can do fine without a shell:

#!/usr/local/perl-5.42.99/bin/perl 
use lib '/some/special/libpath','/another/special/libpath';

# rest of the script here, unmodified
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Perl does not even mind if you prefix those two lines to an existing script, the shebang (#!) line of the existing script will be parsed as a comment.

If you don't want to modify scripts, you can also use a perl script as a wrapper:

#!/usr/local/perl-5.42.99/bin/perl 
use lib '/some/special/libpath','/another/special/libpath';
require '/path/to/real/script.pl';
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(untested)

This simple one assumes that script.pl returns a true value. Alternatively, use do $filename, but that needs more code for error handling:

#!/usr/local/perl-5.42.99/bin/perl 
use lib '/some/special/libpath','/another/special/libpath';
unless (defined(do '/path/to/real/script.pl')) {
    die "Could not parse script: $@" if $@;
    die "Could not read script: $!";
}
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(untested)

Generally, if you run a script as root or setuid root, consider adding -T to the shebang line to enable taint mode (see perlsec).

Alexander