I'm not sure which ripped out files you're referring to. As far as I know, SA1 DLCs have all their data stored on the VMU (two NiGHTS songs on the disk are the only exception), so there aren't any files needed to activate the DLC. I'm certain the DLCs are regionally locked though, but I'm not sure if they're tied to the game's region or the console's region. If it's the latter, you might only be able to enable the Reebok challenge by modding the console itself.
If you're absolutely sure there's a file in SA1 responsible specifically for the Reebok DLC, please do let me know which file it is. I'm interested in reverse engineering SA1 DLCs to recreate them as mods for SADX PC.