Hamilton credit card download procedure is lots of fun and you get to use the $411 handheld. But Hamilton charges you $100 everytime you change your credit card information.
Basically, a Hamilton tech dials into your entry unit and you mash buttons on your handheld. It counts to 5, dials back to Hamilton? Then they restart the credit card computer. Your name comes up on the handheld and you are done. Now you check the credit card reader.