You need the latest DevHook and the 2.82 fw emulated. Launch SFTB2 in DevHook and log online and Download and Install the update that needed 2.81+ to run. After it is done installing, exit the game and restart the psp, now that the update has been installed, you can run SFTB2 from teh 2.71 XMB.
All the Update does is put a update Eboot and a PRX file in a folder int eh GAME folder. Then I assume it is somehow loaded on boot probably because teh folder matches the game ULUS number. So you no longer need DevHook to play the game, just to get the update. Also any Save Games you have, will be corrupted when you launch the game in 2.82, and then again when you are back in 2.71, so make sure everything you have everything backed up before doing this.
Also, to make it so that the Update Eboot doesnt show up in your game menu with your isos and homebrew, just delete the Eboot.pbp int eh ULUS folder for socom. But leve the Socompsp.prx because that is the update.
For those that need one.
1. Get DevHook with 2.82. FW working. Use this tutorial if you need to set it up: http://forums.qj.net/f-psp-homebrew-...v20-81061.html
2. Load DevHook.
3. Launch SFTB.
4. When you get to the main screen, press square for fast login. It will connect you online.
5. Go through all the steps to get online, and you will be prompted to download an update.
6. Download it, and let it install.
7. Once everything is done. Exit the game, and restart the PSP.
8. GO to the USB Connection or if you have a file management program, and delete the Eboot.pbp in ms0:\PSP\GAME\UCUS9845\ (if there is a european or other version, the numbers might be different.)
9. Load up Socom as you would any other game, and enjoy 2.71 online SFTB2.
If you wish, you may download my UCUS9845 folder so you can skip this whole process that I put above (so you dont even need to get DevHook or anything else running). But I can't guarantee 100% working, because I don't know if there are other versions of the game.