What handles a player being banned from the casino? I want to make a terminal that the player can hack in to to make their self unbanned, so if anyone knows it would be very helpful.

If in the geck under Misc, click Casino, then type something in like TheTops in the search bar, you get a Casino data window. This shows the max caps, and all the levels of 'comps' you get as you win. I think there must be a script command to lower the ammount of money it registers as won from a casino. So you could perhaps make a terminal that resets the won value down to 0, and resets all the variables that tell the floor manager to comp you. It will take some looking into, and I don't know the functions needed, but I think it can be done. Between work periods on my Fo3 mod, I check into this kinda stuff (as my first mod for NV will have to do alot with a new casino, and gambling) so if I figure anything out I'll let you know.

How about a "High Roller" perk?

I think this would be a bad direction to take, because it would just start the whole process over again. You'd see the same exact dialogue from the floor managers. I think the best way to do it would be to have two options; either bribe the floor manager with a cut of the action, or like the first suggestion, create a terminal to hack. But instead of the Caps won variable back to 0, just have the original quest script add an extra statement that negates the banned effect afterwards if either flag is tripped from the dialogues.