The problem I would have with applying pressure to the side to increase depth is this:
when we put pressure on top an bottom, the fingers are in direct contact with both sides of both CC chambers. However, if we want to put pressure on the sides, we will only have direct pressure on the outised edge of each of th two CC chambers. We cannot put direct preasure on both the CC chambers individually this way. The pressure we apply, would:
1. Be shared amoung the two CC chambers, unlike with top/bottom pressure where both chambers get 100% of the finger force.
2. Probably some will be disipated/wasted in the compression of the tissue in between the two CC chambers (I am unaware of what this tissue is though).
So effectively we would need twice the force to have the same effect. Sounds dangerous to me!