I see 500 people read your post and not one suggestion to help out this Newbie !
Bert - That could be a tough request to get a few Chica's to join you, However I would personally try a internet search for Jaco/SJO Airport Shuttles and from there I would look for 1 of those shuttle services that maybe mentions & specializes in Bachelor parties to fulfill your desires, both Bachelor and Divorce parties are very common in Jaco that's where I would start.
Keep in mind once you're at the Cocal the options will be plentiful.
Enjoy your trip.