The fact that they could code a graphics engine at all means they could make the needed changes. They have multiple detail levels, and one of the most customizable graphics systems of any game out there. If they have the programing skill to do all that, then making the engine process through the card vs the cpu is probably well within thier ability to do. I would imagine this is handled by DirectX anyway, and all you need to do is call the correct functions.
There were many games that play just fine on geforcemx series hardware, that use the cpu for this stuff as well, yet still use the GPU for it on hardware where it's supported.
If I remember correctly, SOE had a similiar problem with either the 9700 or 5900 series and EQ1. The game wasn't identifying the new cards properly, and was using the cpu to perform the heavy lifting instead. They got it worked out eventually, but it took them a while then as well.
And no, I'm not a graphics engine developer