is it possible to softmod using slayer's auto install 2.5 and memory card/game save exploits? please advise, any help is greatly appreciated.
Yes. You need the gamesave exploit to softmod your xbox. You can do this a number of ways, and I've never used Slayers. You can buy a gamesaves thing from best buy or somewhere and copy the gamesaves onto it then copy them to your memory card (must have) which copies onto your xbox. Run the game that you used the memory card exploit from (007: Agent Under Fire, Mech Assault or Splinter Cell). Install the softmod and voila! Softmodded! (Read the readme on slayers to figure which way to softmod [the games are different]).