The invention comprises methods and apparatus for modifying or converting a gaming machine to permit fully cash-less or optional cash-less transactions in a manner which avoids changing the existing firmware or software of the gaming machine. In an optional cash-less arrangement, a player selects the form by which finds for added or paid to the machine and/or paid out by machine. The cash-less forms of payment may comprise the acceptance and/or payment of funds or value electronically to a system account, coded card or ticket, smart card, magnetic card and other non-cash elements. In one or more embodiments, the invention consists of hardware and/or software for intercepting and/or emulating any or all combinations of the electronic signals associated with the coin acceptor, cash out button, hopper, serial communication interface(s) and bill acceptor(s) associated with a gaming machine to create optional currency transfers. These currency transfers comprise the dispensing or adding of coins, tokens, bills, or any physical item of value and/or any method of transferring funds electronically.