Wooden man training, to me, is simply like working a bag. Its a tool. Try this, try that, see if you can make something work.
Also, its used for hardening the forearms and striking surfaces, and strengthening core muscles. Its a training tool that requires a higher level of mindfullness when using.
There are many kinds, and many placements of the arms/legs. Some on springs, some that slide up and down a wall, some that rotate.
I have not heard of a 'form' per se, but I can see how you could develop exercises that you repeat on the jong regularly.
They are a bit of fun, for sure.
Paperbark trees are the next best thing...
Guangzhou Pak Mei Kung Fu School, Sydney Australia,
Sifu Leung, Yuk Seng
Established 1989, Glebe Australia