If you don't want to loose OtherOS support for the PS3 3.21 firmware update, then HaxNetwork has a tutorial posted that explains how to bypass the newest update and still connect to PSN on lower PS3 firmwares
(3.15 Firmware confirmed working).
Edit: an even better way. Thanks SpartenOmega117.
http://www.youtube.com/watch?v=Vto8ojKeRcE
Easy method wtih installer (requires you to be a registered user).
http://www.haxnetwork.net/downloads.php?do=file&id=269
hard step by step way
http://www.haxnetwork.net/showthread.php?t=9745
Keep in mind everyone this is only to preserve official Linux support and has nothing to do with running pirated software even though that can't be done.