Nicely spotted.
Here's my version.

alias -l spaces { return $+(,%3d.2,$chr(44),%3d.2,_)   }
Menu Nicklist,query,channel {
  .3dtext
  ..on: set %3dtext on 
  ..off: unset %3dtext  
  ...Bold
  ....On: set %3dbold 
  ....Off: unset %3dbold
  .Scheme
  ;####         v-text-v        v-background-v   v-endbrack-v   v-1stbrack-v
  ..Red (d):  set %3d.1 07 | set %3d.2 05 | set %3d.3 01 | set %3d.4 04
  ..Red (l):  set %3d.1 01 | set %3d.2 04 | set %3d.3 05 | set %3d.4 07
  ..Green..:  set %3d.1 00 | set %3d.2 03 | set %3d.3 01 | set %3d.4 09
  ..Blue...:  set %3d.1 14 | set %3d.2 02 | set %3d.3 01 | set %3d.4 12
  ..Teal...:  set %3d.1 00 | set %3d.2 10 | set %3d.3 02 | set %3d.4 11
  ..White..:  set %3d.1 00 | set %3d.2 14 | set %3d.3 01 | set %3d.4 15
  ..Pink...:  set %3d.1 08 | set %3d.2 13 | set %3d.3 12 | set %3d.4 07
  ..BLIND..:  set %3d.1 01 | set %3d.2 08 | set %3d.3 14 | set %3d.4 00
}
on *:Input:*: {
  if (%3dtext) && ($len($1-) < 49) {
    if ($left($1,1) == /) || ($left($1,1) == !) || ($left($1,1) == .) { goto skipper }
    msg $active %3dbold $regsubex($regsubex($1-,/(?!\s)(.)/g,$+($chr(3),%3d.4,$chr(44),%3d.2,$chr(40),$&
      $+($chr(3),%3d.1,$chr(44),%3d.2,\1),$+($chr(3),%3d.3,$chr(41),$chr(3)))),/(\s)/g,$spaces(\1)))
    haltdef

  }
  :skipper
}

Both ryan and I ended up with pretty much the same script. three extra colour schemes (added later) and the command triggers as well as a length check. More than 48 letters/numbers/spaces and it messed up the regex, so I set it to just skip and save the error message. (mine does not have the underline though)
(the bold variable was simply the CTRL+B bold character but hawkee doesn't recognise it, remember to add it in when/if you copy it (line 7) hehe)
Enjoy!
And remember Jethro did the hard work, we just played with it a bit. ;]