Check out Chimensch's YouTube shaving video here, starting at around 5:06. Watch the whole video, it's all great; but the part starting at 5:06 is directly relevant to your issue.
Chimensch's video is deceptive, because it's very subtle and he makes this look so easy and non-dramatic, shaving his neck with his opposite-side hand ATG. But as many great shaving videos as I've seen posted on SRP, I must say that I've learned more from watching this video carefully and repeatedly than any other.
The first time I tried this technique on my neck shown starting at 5:06, I burned my skin up, because I used too much pressure! A VERY light and sure touch is needed, which comes with practice and care. I actually pull up on my earlobe rather than stretch up on my cheek as Chimensch does. But however you pull this move off, it's very effective as part of a 3rd pass ATG neck shave. Watch carefully, and try this. If nothing else, you will learn. Experiment. No one shave will make or break you, this is a long-distance game.
http://www.youtube.com/watch?v=XIM0Coix6Gg