Geoff Mills coughed up some electrons that declared:

On Thu, 17 Sep 2009 11:37:00 -0700 (PDT), "js.b1"
wrote:

...
You can buy cut lengths of 6491X online. TradingDepot, perhaps
AlertElectrical, Gil-Lec, TLC for gr/ye, a few others.

Thanks for the leads. I'll follow them up.

...

If there is no real requirement to use conduit, I would use oval.

Does oval marry up with the surface mounted back boxes in a similar
way to conduit?

No - you'd probably want mini trunking for that.

Although you could use 20mm oval to 20mm round adapters and metal clad
surface boxes (with 20mm conduit knockouts) - though such adapters are as
rare as hen's teeth.

Also, oval conduit is not as robust as round - it really forms a tube in the
plaster. On the surface it would be easy to squidge.