whats the easiest way to fix the rust PROPERLY in the heater channels... (I DO HAVE ACCESS TO A MIG)

To do it properly you should remove the body from the pan.

Does the rust look like this ???????
:bounce

following posts from front to back of drivers side heater channel in my new project

this car is a 67 (delivered may 67) bug in white

front of channel where vent is

next pic ... moving towards the back of car

next pic towards end of door

and finally where the channel meets the take off from the heater boxes

Just incase anyone asks this section is the worst rust in the car and otherwise (and from the outside ) the thing is perfect .... even has all the chrome bits and the horn ring on the steering wheel is complete
the doors close perfectly and there is no external rust at all ....

This one is going to be FUN FUN FUN FUN FUN FUN !!!!!!!!!!!!!!!!!!!!
:bounce:bounce:bounce:bounce:bounce:bounce:bounce:bounce:bounce:bounce:bounce

I've only done this once and found it easier to leave the body on the pan. Cut the old sill completley off by drilling out all the spot welds at the bottom of the front and rear side panels and cutting the welds at the bottom of the door pillars.
Undo all the bolts along the side of the floor pan and the old sill will probably come off pretty easily.
Once you have the replacement sill sitting beside the car it will become more apparent how it is attached. I assume you can still get replacement sills.
I have some exploded views of a mid sixtys beetle in a work shop manual. U2U your address and I'll send you some photocopies.
Dean

woozy, you have u2u.