It's easiest to hit up an ATM at 7-11 (7 & iHoldings, etc) before you get to TDR. You won't have to go out of your way to run into one of those -- They're everywhere.
TDR Explorer had a video showing where the international card friendly ATM is:
http://tdrexplorer.com/using-cash-or-credit-at-tokyo-disney-resort/