Sorry guys about the late reply,
The beads are tied with a (flattened) piece of mono underneath the hook.
They fit in nicely in the bent-shape of these hooks. It's a quite simple way of tying in fact. After securing the bead you can tye the rear part of the nymph as usual. If you get close to the bead you can tye in the legs by using a dubbing loop. This loop can be wrapped around the hookshank, behind the bead (on top a bit more to the front of the fly), or around the top of the bead itself. If you do so you must make sure to leave this top of the bead, closest to the shank, as clear as possible. If not the loop will slip over the bead. Finishing the thorax is standard again.
What I like most about this system is that it's very simple, highly effective and that it might be a challenge for fly tiers to adapt known successful patterns into up-side down ones, which I aspect to be even better. For the patterns I tried it works great (Montana, Pheasant Tail and some un-identified owns patterns, as the second pic shows) I'm always curious about your adapted patterns to this tying style.
BTW I am thinking about contacting some magazines now to see if they are interested in some publications in order to share it more widely.