Yes, I have a similiar setup and its running
I have a PSP wit PSPRadio and am streaming my personal audio files over from the wl-hdd. I searched in vain for a icecast.shoutcast server for wl-hdd, but then just ended using httpd to stream mp3 files over wl-hdd wifi and it seems to work just fine. Install the httpd ipk, put your mp3 files into the httpd www directory, start the service, and then edit your PSPRadio playlist file (stoed int he papradio playlist folder) to point to your wl-hdd ip and port and mp3 file. It will sream the mp3 to your PSPRadio nicely without the shoutcast server. I think eventually a dedicated shoutcast server would be better as it transmits a true stream with metadata info.
Remotely controlling Zina
Try running Peldet on PSP (telnet client) and install the lynx ipkg browser on wl-hdd. Run peldet, login to wl-hdd and launch the lynx browser. You can easily navigate the web-page to make playlist configurations, then use wget command to download, then use file assistant to move the file around on the PSP. I havent tried this yet, but it should work. This way you don't need a pc running or a psp 2.0 browser.