We changed up how this works for Toolbag 5. You can set the UV channel for the material in the Texture panel.
If you need different maps to use different UV channels, you can do that with layered materials. There's a ton of additional flexibility in this case too, you can use blend modes to multiplity, overlay, etc multiple maps on different UV channels. Each layer can have different UV transforms and so forth. You can use this to build really complex tiling detail (detail normal etc) effects.
About a contest, we welcome anyone wanting to organize it, and we can help by hosting files, making a dedicated forum section, etc. But ultimately someone needs to step up and organize, promote, and manage.
There was a suggestion earlier this year to honor Kevin Johnstone by doing a skinning comp using his SDKs. But no one was able to pick it up and drive it.