I tried POE and Threading without success,...

Either is capable of doing what you've asked for. If you've had trouble it's because you've done it wrong. Why not show us your attempt(s) and let us help you correct them?

Update: Just to show how easy it could be:

#! perl -slw
use strict;
use threads qw[ async ];

sub sub1 {
   while(1) {
       print "in sub 1";
       select undef, undef, undef, 0.1;
   }
}

sub sub2 {
   while(1) {
       print "in sub 2";
       select undef, undef, undef, 0.1;
   }
}

async \&sub1;
sub2;
[download]

Of course, it's not very useful, but then niether is the spec :)