http://www.2alien.info/2008/07/hostcore_12_preview.html

Here are 2 binaries of the 2nd preview of hostcore 1.2, almost full function in 4.01, but I get an odd bug in slim psp, the one which output debug info works well when the other one can not play iso game in usb mode. phat psp just all right.
It's NOT a stable version, take your own risk to test it.

hostcore 1.2p2

hostcore 1.2p2 debug

I will glad to receive some feedback of that bug...