...
use threads;
...
BEGIN {
   $Config{useithreads} or die "Recompile Perl with threads!";
} # end BEGIN
...
   switch($action) {
      case /adminpass(,|$)/ {
         print "Do adminpass ($hostname)\n" if($verbose || $debug);
         $t[++$#t]=threads->new(\&adminpass);
         next;
      } # end case /adminpass/
      case /backup(,|$)/ {
         print "Do backup ($hostname)\n" if($verbose || $debug);
         $t[++$#t]=threads->new(\&backup);
         next;
      } # end case /backup/
      case /buildhosts(,|$)/ {
         print "Do buildhosts ($hostname)\n" if($verbose || $debug);
         $t[++$#t]=threads->new(\&buildhosts);
         next;
      } # end case /buildhosts/
      case /buildhostsdell(,|$)/ {
         print "Do buildhostsdell ($hostname)\n" if($verbose || $debug);
         $t[++$#t]=threads->new(\&buildhostsdell);
         next;
      } # end case /buildhostsdell/
etc...