Hi there John. Forgive me if I'm missing the relevant bit in your link, but this page doesn't seem to mention CC at all, having been written in 2011.
However I did find some really helpful - and rather obvious common sense advice - on the below link.
This page seems to offer a solution to the limited card support Premiere offers, by way of a hack... however having myself read that CC 2014 should provide much greater support for a whole mix of GPUs I resolved to try a much simpler solution first which the site also suggests.... and it worked!
I updated my Video Driver from NVIDIA direct instead of from the MANUFACTURER'S site! I'd always assumed you needed to go to the manufacturer but, of course, Nvidia are constantly updating drivers and the manufacturers don't bother toupdate their sites! So I'd actually got extremely out of date drivers installed. I can't believe this basic maxim has evaded me so long. It explains past issues I've had as well. But having installed from Nvidia CC now lets me use Mercury with GPU. So I'm very happy atm.
Thanks for your help.