Hunt or Calling Groups that will ring exts even when on another call

[classydreams]

I am trying to program a Partner 6.0 that is set up for POOL mode so that when calls come in on one of eight CO lines all sets will ring even if the ext user is on a call. From what I see if they are on a call a HUNT will bypass them and I am not sure if Calling Groups will work. The pool only gives me 2 lines on 880 and a single lines for 882, 883. The rest of the 18D buttons are used for features and intercoms. What is the best way to do this?