You need a heat gun like the plank flyers use for shrinking Monokote or Oracover. Commercial versions are used for removing paint. You could try a blow hair dryer but I don't know if it gets hot enough. Do not use an open flame of any kind on your heli.
Here's an example of a heat gun:

http://www2.towerhobbies.com/cgi-bin...?&I=LXL498&P=7

Cheers - Boyd
AMA 80393
Major USAF
Retired