Subirrigating bonsai trees?

Is it possible to subirrigate bonsai trees? Has anyone had any luck with that? And if normal bonsai potting mixture doesn't suck up water that well, is it possible to add a little clay or something to the mixture to make it suck up anough water, without for that matter making it bad in some way for the tree? I have two bonsai trees — an oak and a juniper — and I would really like to subirrigate them if that is possible.

Here is an idea I have: What about planting the trees only in leca pebbles (expanded clay pebbles)? The pebbles can suck up water; I think they could be used to transport water up to the plant, and the air will be able to circulate freely around the pebbles. What can go wrong?

Edit: It is this kind of subirrigating system I have planned to use:

Nice video and idea, but I would be very afraid of root rot.

What about if you plant your tree in only leca pebbles? Wouldn't the air be able to circulate freely around and between the pebbles, giving the roots all the air they need?

I think the idea of constantly wet substrate would only benefit certain species, most would not appreciate those conditions and root rot would certainly be a strong possibility - if you were to try this then start with only trees which you don't value highly.

Dave