This is the best that I've managed so far:

while (($k, $lref) = each %HoL){
  $HoL{$k}={map {$_,1} @$lref};
}
[download]

I tried to get something along the lines of the following bit of code to work but couldn't:

%HoL=map {map {$_,1} @HoL{$_}} keys %HoL;
[download]

I'm sure merlyn could blow this out of the water (and I hope he does, I'd love to see his solution... probably something really slick w/ 2 maps)