Let's make two assumptions:
1) I have a Xara binary with built in Pantone support 2) That binary is not stripped.
If I have the source code I should be able to figure out which function calls deal with that library, and I should be able to dynamically load the Xara binary and call those functions since I know the prototypes from the source code, and if I used the same tool chain. Could we get Pantone support? Users would have to buy the full version of Xara to get it, but for most people who need Pantone, that wouldn't be a big deal.
Probably a better solution is to convince Xara to break their color management out into a GPL'd library. Then they could sell a proprietary version of that included Pantone support. Then we could link to that library. If it was generic enough, Scribus and GIMP might be interested also.
Anyway, I've never thought about dynamically loading an application before. Crazy.
--Ted