No it's called action replay thats one of the cheat devices for the psp and im sure they got couple of codes for this game.
Maybe theres more devices like this but i only know this one.
You can get probably any soldier you wan't even them Patriot soldiers or something that you were talking about (miles thompson) with ease but that's pure cheating and just so you know i don't have one.
(PS2) Dragon Ball Z Budokai Tenkaichi 2 Dead Goku Password :
tnTB tpbj ?Bl? navs
-O*F *!Jj SN*s Uuds
(DS Friend Code) Final Fantasy III : 137544574557
(DS Friend Code)
Pokemon Diamond
Name: HANZ
Friend Code: 4639 6323 8084