Root over rock: How to secure rock to pot?

Hello!

I have a couple of ROR bonsai that I'm developing. At the moment they're in the ground and growing.

When I eventually get around to potting them up, how should I secure the rocks to the pot? I'm thinking of gluing lengths of wire to them, then tying the wire to the pot as you would normally wire in a rootball. Or, gluing some islets to the rock which I can then pass wire through, then wire to the pot.

Does this sound like a good idea, and if so do you have any suggestions on what sort of glue should be used?

I currently have a field maple (A. campestre) and cotoneaster (C. horizontalis). I'm thinking of starting a few more this weekend, can anyone suggest a couple of decent strong rooted species that take well to this technique?

Cheers

Acer buergerianum of course, and A. palmatum too.

To secure the rock to the pot, I once made a thin sole of cement (the type used for drains, fast drying and very hard). Since the base of the stone is under the soil, I thought it was not a heresy. Then, securing wires that came from the draining holes around the base was easy and efficient.

Thanks Alain, seems like a pretty sensible idea. None of the rocks I'm using are that large or heavy so a cement base should do the trick