My gel pad arrived while I was away on vacation so I got to work installing it today.
The installation procedure is pretty easy but once you begin you're committed.
The pad I bought was 9"x10" and 1/2" thick and cost $26. This is a great deal because if you look around the web, all that's available are pre-shaped pads that seem to start at about $50 for a size that might or might not fit the Ruckus seat. I looked pretty heavily into the medical industry online (for wheelchair users and the like) but couldn't find a sheet of gel this size and price. http://www.diymotorcycleseat.com
has this deal!
This pad is oversized by just enough that you can trim it to the shape you want. I wanted the pad to remain on the flat area of the seat, and trimmed it to shape with scissors. Dust flour along the edges as you go because when you trim it, the edges are extraordinarily sticky. The flour makes it much easier to work with (the instructions recommended this). I didn't take a picture of the pad before starting work, so just imagine a rectangle just a little bigger than this.
I laid the pad in place, traced around it on the foam, and began to cut it out.
I used a serrated knife which I marked to 1/2" depth to cut into the foam. I cut about 1/8" inside the line I had traced. Once you have the outline cut, cut strips in the foam. Then remove each strip to 1/2" depth. The easiest way to do this is to pull up and back on the foam strip, and carefully saw at the base. If done right the strips come right out to the approximate depth.
Then, roughly smooth out the base and lay the gel insert in.
It was a good idea to cut 1/8" inside the traced line, because you can gently squeeze the gel pad into place without any gaps. It fits snug and after letting it settle, you can see which areas need a bit more shaving.
I worked the foam (gently shaving away at it with my serrated knife... a cheap steak knife, in fact) until it was even. Once satisfied, I sprayed some craft glue into the cutout and laid the gel insert in evenly.
After you have the insert in place, it's a good idea to put some smoothing foam over the whole seat pad. This will smooth out the shape of the seat and keep the parts that you shaped from looking rough and unfinished. What I found at the craft store is some headliner cloth which has a thin foam backing.
Spray glue over the seat, put the foam in place, and stick it down over all the curves. Stretch and add more glue as necessary, then when it's glued down sufficiently, trim around the edges with scissors so it's even with the foam.
At this point you should be ready to re-cover the seat.
I don't have my final seat covering material ready yet so I just did a quickie job (like 10 minutes) with some vinyl from the craft store so I can ride in the meantime. The stuff I bought is the wrong kind, it has a weak cotton-wool backing. What you need has a kind of stretchy fabric backing (that's what the stock Honda seat is made of). The cottony backing is easily torn through by staples and doesn't stretch well. I'm ordering some carbon fiber vinyl and will probably just make a single-piece seat cover, though I might stitch a couple of pieces together with some contrasting red thread for a more custom look.
A job well done. I'll post again when I actually finish the seat with a good-looking cover without wrinkles in it!