Something you may want to try - and depending on your company policy may or may not work ... when you check in ask to be taken off the master bill.

I have one meeting a year which is master billed (our annual convention) and its one of the very few meetings or trips where I don't make the hotel selection. Whether its a Hilton (2002 and 2000), Hyatt (2001) or Starwood (1999) I ask when I check in to be removed from the master bill. Then I pay and submit for reimbursement along with the other expenses (airfare and meals, etc.). I haven't had any complaints from our accounting dept. although I would have thought they would find it odd that I was the only employee (I think I'm the only one) of the 40 or so at our convention that's not on the master bill.

The only time I couldn't do it was when my room was comped as one of the freebies built into the contract (our convention attracts 20K attendees - so we fill the hotel, as well as most others in the area).