Hi everybody... (missed y'all the past couple of years)

I discover that my Cattleya walkeriana alba 'OK'
(pix on my website:
www.kiva.net/~daylight )
is in poor shape. I have overwatered it several times recently, and
most of the roots are dead. :-( This is depressing as it was in
fine shape for two years and, I thought, now ready to divide.

What is the best way to recuperate this plant, and can it involve
giant pine bark chips?
I'm thinking that it needs to be repotted in a very, VERY open mix.
I don't want to use things like cork chunks, or styro peanuts, beause
they float. I got a bag of that outdoor mulch, "pine nuggets", which
is big chunks of pine bark. They look to me the right size, but need
to be sterilized (after the nematode incidents, I'm paranoid).

Would cooking them in the microwave, the same as pasteurizing soil,
work?
Would the very center of the bark chunk get hot enough? It wouldn't
be wet on the interior, only hot. Maybe I should bake them in the
oven instead.

The Cattleya is in two pieces, each of which has only a couple of good
roots.
I hope that I can choose a suitable potting mix for this situation,
one in which the plants get enough air to grow more roots. I worry
not knowing what best to do.

Any info on sterilizing this bark would be great.

Thanks,
Liz
Indianapolis, Indiana, USA