I like ferreira's approach better than mine, but, in the spirit of tmtowtdi, here it is anyway:

package myfile;

use strict;
use Exporter;
our @ISA = qw(Exporter);

# Setup the variables with values
my $list = 
'our $myvar   = 42;
our $another  = 1234;
our $yascalar = 3456;';
eval $list;

$list =~ s/our (.+?)\s+= \d+;/$1/g;
our @EXPORT = split("\n", $list);

1;
[download]

Not nice, but it works. Be particularly careful about whitespace when declaring the variables, it may affect the RE.