My car was registered last year. I have an autotechnica wooden wheel with metal spokes. The guy at vic roads did not accept it and said that the metal spokes had to be padded.
I went to clark rubber and bought some rubber tubing. I put the tubing around the spokes and centre (just cut out a hole for the horn). I covered the whole thing with black tape. It looked crap but it passed. I will put a picture in my gallery.
As far as I am aware it just has to comply with the regulations, it does not matter whether or not it looks permanent
Its like putting black tape over the chrome bits (windscreen surround etc.). They know your going to take it off but so long as it complies at the time you should be OK.