I'm using a Genus Babyface head and Belleza body, if that helps. Lelutka hasn't updated yet. LAQ and Slink have. I think you can use Maitreya and Catwa if you have the Omega applier for both of them. I'll try it and see.
ETA: Yeah, it works on Maitreya and Catwa if you have the Omega relay for both of them. Then you buy the
Bakes on Mesh hud in the Marketplace and wear all three of them. Wear your body and head with alphas. Click on all three huds to make sure they're loaded on the mesh. Then click on the skin in your inventory you want to wear (old system skins). Your face and body should turn red (this is how I know it's working). Take off the alphas. Your new skin should be applied. I had to mess around a bit with the Catwa, but it eventually worked. You don't need to wear the alphas when you first start, it just gave me a visual indication it was working.
ETA: Oh, the eyes are wonky on the Catwa. I just took them off and used the AVI Glam eye meshes and hud.
ETA: Bakes on mesh also works with Lelutka heads. Wearing my favorite head with the omega relays for Maitreya and Lelutka Chloe 3.3, plus the BOM hud, and an old Curio system skin.
Bakes on Mesh with Lelutka/Maitreya by
Sansarya Caligari, on Flickr