The only solution I've found so far is to grab Skyfire (go to skyfire.com on your phone), install, then go to Slacker.com and log in. It worked on my HTC Touch Pro. Make sure you select whether you have touch screen or not before downloading CAB file from Skyfire.
Hope this helps. It's not perfect, but better than nothing (which is what's currently available as far as standalone apps) if you want to use Flash sites on your PPC.