I personally found the best way to do this way to get a socket set. What you do then is select a socket that fits over the motor wheel and attach it to a straight bar. Put the belt around the wheel and then around the bar of the socket and then put the socket over the end of the motor wheel. You then will be able to lever the bar straight. You then need to prise the belt on to the socket so you can slip it easily on to the motor wheel. You may need to get someone to do this for you but I managed alright on my own by holding the socket bar in between my knees, though I don't recommend doing this really, best to get some help. I managed to prised it on using two screw drivers for leverage to snap it on to the socket, but again only do this if you are confident in doing it. Slipping could easily result in the belt snapping one of your tools back at you and possible in the face. I suppose you could feed some of the belt on to the socket and then turn the socket around to get it on there (this has to be easier than trying to feed it on to the large drum wheel. Once on the socket it can simple be pushed off on to the motor wheel. It's the easiest way I found to do doing it.
Oh and a bit of advise turn the wheel by hand to make sure it is on properly otherwise it may come straight back off once the machine tries to turn the drum and then you have to strip the back panels off the machine all over again. If it looks like it is coming off then adjust where the belt is sitting on the motor wheel threads. On my machine the belt had to sit flush with the edge of the motor wheel but this might not be the case for your machine.
Hope this helps. :o)
Jenny, June 2006