whoa it's so cool you are helping me (and other croc users) out on this! I tried the beta version, but may be doing something wrong tho. If I export to .obj from Crocotile (a model with vertex colors obviously, and checkmark "Vertex Colors") then add mesh into Penguin they should be showing up, right? It's still blank for me. The creator of Crocotile told me this when I asked, dunno if it helps:
"crocotile adds the vertex r g b values to the end of the vertex x y z data in the .obj, if vertex colors is checked on export.. it's not a standard of obj, but some programs might read the vertex data such as MeshLab."