There are other styles of pants. Some have elastic and bujin has elastic waists, a belt and has a zipper even.
As for the belt, you can try a few different ways and this is one of them. You start off with the tradtional way. After you wrap it around and have it at the front, cross left over right and bring the belt up and behind both layers of belts (not just one), then do right over left to finish the square knot.
This is the little trick: Once that is done, you can take the right end of the belt and bring it up towards your face. Then stick it down between the two layers of the tied belt and then pull it tight in the direction towards the floor. Then do the same with the left end, but this time on the left side of the knot. It will give you an extra way to keep it secure. Just ask your sensei to make sure it is alright. I am having a hard time finding a pic of it though... but I did find this video and it looks like he did what I mentioned
http://www.youtube.com/watch?v=bTxgM...eature=related