If you add suspension to a unicycle, you alter the distance between the pedals and the seat, this makes it quite strange to control. Some people have experimented with parallel suspension seat posts, but as with most mountain bike seat posts, they are designed for forces to work up and down, using them for a unicycle adds a lot of twisting motions and that causes problems. The way a lot of people get around this is normally to fit a large tyre on a strong rim, that way the tyre acts as your suspension.
If you need help RealMan,Unicyclist.com is a really good site, there a people posting from all over the world, and they are a good lot.
Innes