Old thread, but I'll throw this in anyways...

They make silicone rubber flexible waterproof keyboards for not too much $$$. A quick search of Amazon shows a bunch for about $15USD; search terms were "rubber waterproof keyboard". Likewise, searching for "USB trackpad" or "USB touchpad" yields a bunch of results for not too much $$$.

For the touchpads, I might think about opening the case on them and sealing them with electronics-compatible silicone.

Also, Arduinos with native USB (for example, Leonardo, Zero, and Due based boards) can emulate a USB keyboard or mouse; if you're at all comfortable with writing scripts or programming.