It's hard to search for "ace" since it's such a common word. I found and tried UnAce for Linux but it wouldn't run in the Terminal ("binary file not executable" or something to that effect). I thought Unix/Linux apps were supposed to run in OS X? Maybe it's only compiled for Intel or something.
I'm sure there will be a solution out there somewhere, if nobody has any ideas you could send off an email to the WinAce company and see if they know of a compatible product. Good luck!