A month ago a member of this forum asked for the very same thing and I created a cps2emu version with configurable buttons. Unfortunately I hadn't the time to code a graphical interface as well, so you can only pass parameters to the emulador and hope for the best. Besides, I am not interested in this emulador any more since I moved to FBA.
So, I have a basically untested version of cps2emu with textbased configurable buttons. This means a bit of work from you and a basic code experience. If you are interested in testing even if I don't solve the bugs, please send a private message to me.