I find heel-toeing on the street is much more difficult. You don't have the brake pedal depressed as far or as hard on the street so you have to reach for the throttle. On the track, the brake pedal is buried in the carpet, it's much easier.
I'd just practice blipping the throttle and downshifting (no brake) since that is the most complicated part. Get that down and then start adding the heel toe part.
Sponsored by Momentum BMW #593...We Bleed BMW BLUE