The PSP Emulator for windows has been updated, heres whats new:

Draft version of adhoc networking: adhoc network is emulated over the existing infrastructure network. It will only allow adhoc communication between two Jpcsp (on the same or different computers), but not with a real PSP.
Still a prototype and not yet really working. I've managed to have the homebrew Quake Arena Arcade working with adhoc network between 2 Jpcsp running on the same computer.