If things haven't changed since August '04, HP employees are given access to a nice lounge area which is upstairs overlooking the indoor queue for MS. To get in, you must show a valid HP ID which admits you and your guests (you also sign in upstairs but don't know what info you have to provide). The lounge area is nice with complimentary soda, restrooms, a few games for kids, internet access I think and nice seating area. When you want to go on MS you're taken down and put in the FP line. My BIL (an HP employee) and I went on the ride while my DH and DS waited for us in the lounge which was no problem. After getting off we went back up to the lounge, hung out a bit more and moved on.
HTH and have fun!