I also have bveen taught several. For me, Ikkyo is one of the most difficult techniques. At the moment for me works best: unbalance the partner by bringing his ellbow in the direction of his head so his spine has to move. Then ellbow down. But it depends on your partner. With some, this doesn't work, so I choose an other of the variations which seems more appropriate to me.
We do the pin as you describe and I do know only one variation: instead of using my inner hands tekatana to bend the ellbow, I (normally don't use) my inner knee. This is a very hard and dangerous variation! So we don't really practice it.
Hope this helps,