Holly,
I have about 60 going in my basement right now I got as cuttings from UCal Davis. While they are trying toroot, I keep them on a thermostatically controlled heat mat at 74 degrees. Once they have rooted, and I have re-potted, I just keep them under Fluorescent lights for 17 hours a day.This must be working because some of the roses I started on 11/4/05 are rooted and flowering (El Capitan, El Cid, Virgo, Pacifica are blooming right now). I took the instructions provided by George Mander, and tried different experiments to see what would work best for me.
Two of the changes I made were the rooting medium (I swear by coconut coir) and the pots I use for rooting. The pots I use are 2.25 square x 3 1/4 deep, and clear, which means I can see the roots as they are forming. I find great satisfaction when checking cuttings and seeing the roots actually growing.
Let me know if you have any questions. To check out some photo's frm my gardens, you can click on the link here.

Here is a link that might be useful: Gleason's Michigan Rose Garden

Personally...I think HT's are harder to root than OGR's are.I have the best luck rooting anything using dormant cutting and planting/sticking them straight in the garden soil with mason jars over the cuttings.

I don't grow lots of HTs but the few I do grow root rather easily compared to the OGRs and antiques I have. Those HTs that root easily for me are Radiance, Red Radiance, Lafter, and Midas touch.