Here's how to Mod your XP for online play in Red Faction : Guerrilla.
1) open your PROFILE in any hex editor.
2) do a hex search for your current XP, or search for RFGP in text.
3) change your 3 XP values to "FF FF FF".
4) save your file and rehash.
This will unlock all weapons, maps, gametypes and XP for Online play.
This does not affect the campaign of the game or the Leaderboards.
Credit Goes To JizzaBeez