Sadly, you cant edit a player's actual position for the PS2 version. You can either use the substitutions option to have OLB's play at ILB or can find two players that have the same years pro as Witherspoon and Isiah and simply overwrite them. Then add them to the Rams and remove the originals.
You can only edit a player's position using Finn's editor which is exclusively for Xbox. Quite honestly, I could never ever go back to playing 2k5 on PS2.
I checked out tpaterniti's roster last year before I purchased an Xbox and while his roster is okay, it doesnt even come close to the rosters available for Xbox. That's not an insult or being disrespectful to tpat or anything like that. It's just that, 2k5 on PS2 has so many damn limitations that it makes it impossible to create a perfect roster. And for the record, I tried to create a 2k6 roster for PS2 but quit two weeks into it because the limitations just pissed me off to no extent.
I will give tpat credit though. He has managed to create a roster for the 2k6 and 2k7 seasons. Hell, he's the only one that has even managed to create a PS2 roster period.