There is no need to heat the cannabis if it's properly dried, you are just losing some of the good stuff to the air if you heat it to 300.
All the good stuff is gone by about 375.
All you need to do is get a glass jar and add the alcohol, add the cannabis, in a pot of water heat the alcohol in the jar to 140 and let it simmer for 20 minutes and then put it away in a dark place leaving it alone for 2-3 weeks.

There is a great FAQ for green dragon here, follow it and you'll be fine.