There is no hdd or hdf support yet, but I know FOL is working on it.
Depending on compatibility and memory needed, you can still get your HD installed games to work in PSPUAE.You need to make a boot disk that puts all the needed files into RAM and then run the program from there. This takes a while to do, but there is a clever way to speed up the loading and that is by using save states like the ones on the home page. These basically store all the information loaded into RAM and can make your game load where ever you started the state from.
Heres link to some threads on the site that might help.
http://pspuae.condor.serverpro3.com/index.php/board,19.0.html.
If there is a particular game you would like to be made available, then just post a new topic in the save states request topic in the forum and I'm sure me or one of the other RAM installers will help you out. If the game you want will work on PSPUAE, then Im sure it will take no longer than a day or two(maybe less) for someone to make it and stick it on the homepage.
Hope that helps at all.