I tried doing a ruleset before for these, i think it safe to say, i found it way to complicated to get my one working.. I had dreams of a Swarm of several types of chrysalids plus zombies that can hold weapons but couldn't get the basics working 
I simply made some copies of the Enforcermod/Scout Drone ruleset and adjusted the STR_ stuff, now i can/hire Mercenaries (green soldiers), Aquatoids, Tasoth, Lobsterman, Green (terran) cyberdisks, Cyborgs, Tenatculats, Xarquids and Gillman. I used the TFTD_to_UFO unit file conversion from the strategycore file section and the recoloured battlesprites mod, most of the units from those packs work, some don't. I also made some new recolored units myself , blonde civilian females, grey sectoids, red ethereals etc etc. Can't upload them atm as I am sitting in an Internet Café and the explorer here can not see my hidden folders on the USB stick