Adding custom rosters:
Setup a memory card, then navigate to it ie. Documents\PCSX2\memcards
Download the roster files, unpack them into a folder location
Download mymc-alpha-2.6 app (google it)
Launch mymc-gui.exe, then navigate to and select the memory card you created ie. 2k5.ps2
Click the import button, then navigate to the roster.max file, click ok and it will be on your memory card
Close the mymc-alpha-2.6 app
Launch the game and go into options, load/save, select the roster file and load it
That's it, now you have loaded custom rosters.
Enjoy!