I've read both http://thesandtrap.com/t/58953/is-it-legal-to-use-your-putter-to-line-up-your-putt and http://golfrules.freeforums.org/line-for-putting-t1833.html as referenced in Dormie's post and I figured I'd throw in my tuppence worth. It would probably be more appropriate in http://thesandtrap.com/t/58953/is-it-legal-to-use-your-putter-to-line-up-your-putt but I didn't want to bump a nearly year old thread.
Anyway, the point that strikes me about the language of 8.2b is "... may, before but not during the stroke, point out a line for putting,"
There seems to have been a lot of discussion about where the 'line for putting' is in relation to the 'line of putt' as discussed in 16.1 but the point I haven't seen made anywhere is that the language 'line for putting' seems to me clearly intended to indicate a point at which the ball would be aimed.
Thus, any point on the green in a direction opposite from that which the ball will be traveling cannot possibly be used to 'point out a line for putting'.
Can't you use a point behind the ball as a basis for your aiming line? It might not be the most natural way to do it, but a point behind your ball and your ball are 2 points that define a line and it would be possible to think about your aiming line this way., wouldn't it?