I have skinned hundreds of doors in the last 35 years.If you do not own a skinning hammer you may wish to farm out the tr4/6 door.The angle of the lower lip is too tight to the edge of the shell for a regular hammer to hit squarely.
If you can borrow one go ahead,its a walk in the park,mostly.
pointers......Get a small block of pine and wrap it with duct tape,use this as your dolly it will not damage the pristine finish of the outer skin.
de-rust your casing carefully and use a weld through primer.
as mentioned earlier, once crimped onto the casing,fit the door to the car!!!NEVER weld anything till it fits like a glove.
once fitted dress off the edges and mig weld the skin in place with a heat that doesnt penetrate the outer panel.stitch it every 4 or 5 inches.
buy a good sound deadener pad for the inside of the skin at a stereo shop it should self-adhere.
after the welds are dressed,etching ,priming and seam sealing are done before paint.Lastly the outer panel rustproofing is applied(waxoil,kent etc) it should flow into the crimped seam to seal it off.
if you try to do this with acetaline, be sure to get really drunk first,a poor excuse is better than none...
MD(mad dog)