red.vulpes.com:~% more t.pl

BEGIN {
    unshift @INC, sub {
                      my($self, $file) = @_;
                      print "loading $file\n";
                      return
                  }
}

use Foo qw(t.pl);

print "in t.pl\n";

red.vulpes.com:~% more Foo.pm
package Foo;

use Bar qw(Foo.pm);

sub import {
    local $" = ', ';
    print "Foo::import(@_)\n";
}

1;

red.vulpes.com:~% more Bar.pm
package Bar;

use Foo qw(Bar.pm);

sub import {
    local $" = ', ';
    print "Bar::import(@_)\n";
}

1;

red.vulpes.com:~% perl -w t.pl
loading Foo.pm
loading Bar.pm
Bar::import(Bar, Foo.pm)
Foo::import(Foo, t.pl)
in t.pl