Do a require and import for package Bar:

package Foo;
require Bar;

sub import {
    my $class = shift; # first param is class name

    if (@_) {
        Bar->import(shift); # that's passed along
                            # with 'use Foo qw(x);'
    }
}
# more stuff...

1;
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package Bar;

sub import {
    my $class = shift;
    if (@_) {
        my $x = shift; # passed from Foo
        warn "$class: got '$x' from ".caller()."\n";
        # now do whatever you like with 'x'
    }
}
# more stuff...

1;
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and then...

#!/usr/bin/perl

use Foo qw(blorf);
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...or even

$ perl -MFoo=blorflydick -e 1
Bar: got 'blorflydick' from Foo
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