i'm not an expert heel-and-toe-er, and it is not yet programmed into my reflexes.
however, the pedal placement of the car makes it easy to heel-and-toe: the gas pedal is hinged at the bottom (sometimes called organ pedal-type) and is slanted to the right, with the brake pedal slightly above the hinged bottom.
This makes it easy to leave your right heel where it is, rotate your foot to the left to brake, slightly raise your right heel to blip the throttle, and perform your double-clutching.
i first learned the technique on a VW Beetle, which has the gas pedal also hinged at the bottom.
for gas pedals that are hinged at the top (called pendant-type), a variation of heel-and-toeing is used: instead of using your heel to blip the throttle while braking, use the right side of the ball of your right foot. I have difficulty doing it with these types of pedals.
I believe there are aftermarket parts for certain cars that are attached to the gas pedal, increasing their surface area, making it easier to heel-and-toe.
happy heel and toeing ...