What rim tape? Is it thin plastic or thicker cloth tape?
Your Aerohead rims look similar in cross section to my old Kinlin rims. The "well" in the center was very shallow, so there wasn't much slack to pull the bead over the edge of the rim. It was so tight that even with just one bead in the center, no tube yet, I couldn't slide the tire around to line up the label with the valve hole. That's tight!
I really struggled, with mangled levers, and sore fingers. But I found a technique that works very well -- see the link below.
Just one lever is needed to mount the tire -- the key is to lift less than an inch of bead at a time, slide the lever over, and repeat. Fast and easy.
Pedro levers are the best.
Aerohead:
Kinlin:
My old thread about mounting tight fitting tires will help.
Inflating the tube slightly when inserting the tube, and making sure it's up in the tire away from the bead is critical, too.
I think your bike store mechanic didn't have very good technique. Not all mechanics use effective techniques.
How to: Tight fitting tire - easy mounting