Poses should be reasonably easy to produce. Simply go to blender, move around a toon which uses the "default" or "default no toes" skeleton, and then do file->export->BVH. The BVH file is what you upload as the pose. Optionally you can also write a ".meta" file for the pose. This is a text file with key/value fields describing the pose. For an example of how it looks, see the fight03 pose.
Rigs however is another matter entirely. Theoretically you can use the io_mhrigging_mhskel blender plugin from makehuman-utils to create it. Unfortunately, the documentation is largely non-existent, and the tool does not help you finish the whole process: You will have to manually edit the resulting files and figure out what to replace a series of null values with. Do it wrong and MakeHuman will crash when you try to use the rig. At this point the area is mainly here in order to allow upload of some old rigs that had got lost in the process.