Tutorial Made By Me:
Ok first of all i don't know if there is already a tutorial on how to do this, but this is my way it works like all the time.
Okay so here goes..
Start off by booting up your PSP in Recovery Menu Then go to "configuration" and go to where it says "Fake region" and change it to "Europe" once you have done that go exit the Recovery Menu and start your Syphon Filter Dark Mirror Game/ISO, And go to "Multiplayer" and then "Infrastructure" and you should log in..
If it doesn't go to your router and turn it off for like 5 seconds and turn it back on and try again, Most of the time this method works.
-VaLcOrN
+REP If it works :]