We have purchased Roma passes, we are unsure if we will have used our two entries before we get to the Borghese museum, but we want to reserve our time slot ahead of time-
I see there is a phone number to call and reserve as a roma pass holder, has anyone done this? What information do you need to give them over the phone, I have a roma pass confirmation number...
In our case, we had the hotel make us a reservation, and then used the Roma Pass to 'buy' the ticket at the counter. The hotel had no idea we were planning to pay with the Roma Pass, so my best guess is that you simply make the reservation separately and if you have used your roma pass up by the time you get to the Borghese, you can just pay the ticket out-of-pocket.
If you have a hotel lined up, might want to try to delegate the task of making the reservation to them. Otherwise, I would expect that if you call the reservation number, you will tell them the date and time you want, and pay the reservation fee (which isn't covered by the roma pass anyway). Don't think the roma pass confirmation number is necessary--we never had one because we bought it directly at Termini.
Amy: You are aware that reservations are mandatory for the Borghese, not optional?