Zx-81 has released PSPHugo today, a PC Engine emulator port for PSP based off the latest version of Hu-Go. For those who don't know, Hu-Go is a famous emulator of NEC PC Engine console, running on many systems including Linux and Windows.
According to the author, it's a first release, work still remains to improve the speed and to fix graphical glitches on games such as gunhead.
Download: PSPHugo v1.0.1 for CFW 4.X / PSPHugo v1.0.1 for FW 1.5
From the included ReadMe file: Unzip the zip file, and copy the contents of the directory fw4x or fw15 (depending of the version of your firmware) on the psp/game, psp/game150, or psp/game4XX if you use custom firmware 4.01-M33.
In the PC-Engine emulator window, there are three different mapping (standard, left trigger, and right Trigger mappings). You can toggle between while playing inside the emulator using the two PSP trigger keys.
You can also use IR keyboard. Edit the pspirkeyb.ini file to specify your IR keyboard model, and modify eventually layout keyboard files in the keymap directory.
If you want to load rom image in your emulator, you have to put your rom file (with .pce file extension) on your PSP memory stick in the 'roms' directory.
Then, while inside emulator, just press SELECT to enter in the emulator main menu, choose "Load Rom", and then using the file selector choose one rom image file to load in your emulator.
For given games, the default keyboard mapping between PSP Keys and PC Engine keys, is not suitable, and the game can't be played on PSPHUGO.
To overcome the issue, you can write your own mapping file. Using notepad for example you can edit a file with the .kbd extension and put it in the kbd directory. More PlayStation 3 News...