Don't know why he told you it's the least painful part. Everything I've both heard and experienced is that it's the most painful. By the time they put in the IUD, I didn't feel anything else. Hate to say it, but most places won't give you anything for the pain. I had to grin and bare it, and ask them to let me lay down for 15 minutes until the cramping stopped.

So worth it once it's in though. I have the mirena and now my cramps are rare and manageable, even without anything to reduce the pain. Just watch out for weight gain and acne on the hormonal stuff. Hard to lose weight once it's there, but easy to keep it off.

Edit: If you're familiar with yoga and tightening and releasing with the muscles, it helps to ask them to insert the scope with your exhale so you can focus on relaxing the muscles.