My desk doesn't permit that and I like it higher anyhow, so I lean back in my chair and simply put the keyboard in my lap. Once you're used to it and relax, it meets all ergonomics criteria I've seen; flat, comfortable wrists, no stress or strain, etc. It's a Microsoft split keyboard, which helps, but my non-split laptop, which I use in the same position, is fine too.
(Also, I think switching to Dvorak may be helpful. My wrists move a lot less with this layout than they do with QWERTY. Touch typing is a good idea but where QWERTY discourages it, Dvorak makes it simply the best idea; you don't have to try, it just happens. YMMV; please note I said "I think", and I mean exactly that, not "It has been proved that".)
Anecdote: I typed ~95 WPM on Qwerty, hunt-and-peck* , and switched to Dvorak three or four years ago. Touch-typing Dvorak just feels natural to me, too. I haven't measured my speed in a while (over 60 WPM, who cares?), but Qwerty feels like a chaotic jumble by comparison. It's mostly a comfort/ergonomic issue for me.
It's a tricky thing to get hard data about, though, and the whole Qwerty vs. Dvorak thing somehow got caught in some religious argument about the free market, so there's probably too much noise to ever sort it out.
* Hey, I taught myself to type on a Commodore 64 as a kid.
(Also, I think switching to Dvorak may be helpful. My wrists move a lot less with this layout than they do with QWERTY. Touch typing is a good idea but where QWERTY discourages it, Dvorak makes it simply the best idea; you don't have to try, it just happens. YMMV; please note I said "I think", and I mean exactly that, not "It has been proved that".)