Hi B.,
I had this test done the first time I was trying to get pregnant. It wasn't pleasant but I saw it as a neccesary means to an end. I now have a beautiful little boy who just turned 4 (conceived through IVF) and I'm expecting baby #2 in March, also conceived through IVF. Everyone's pain tolerance is different. I did cry during the procedure...partly because of the discomfort but mostly becasue of why I was having this test. I really didn't know what to expect beforehand so I went alone. If possible, have your husband or a really close support person with you, especially if you are nervous. It is a procedure done in radiology so just remember that if your support person is female, she will not be able to stay in the room with you if she is pregnant.
As far as the pain is concerned, to me it felt like really bad menstrual cramps. I think I took a couple of Motrin both an hour before and right after the exam...double check with your doctor. The pain is only temporary and again it's a means to an end.
Feel free to contact me if you have any more specific questions or concerns.
Good luck and try not to stress about it...I know, I know, easier said than done :)
D.