I just upgraded from the g1 to the mytouch slide and I really miss the end and send buttons.. Can you change the genius button with an app or something to funtion as an the end button?
Maybe it's possible some kind of way after rooting your myTouch Slide. I'm new to Android so I don't know much, but you can go check out the XDA Forums, they have found a way to root it.
After looking at the XDA Forums I found a post with instructions on how to remap the Genius button: [how-to] remap genius key, but of course you need to root your myTouch Slide, I haven't tried anything, like I said I'm new to Android