Hmm. after looking at this some more, I found a utility called disabler.exe that comes with Microsoft's DDK. You might try using that. The documentation on the CM_DisableDevNode function under the cfgmgr.h (cfgmgr.dll -- PNP configuration manager) is non-existent because Microsoft doesn't want people messing with it. Otherwise, you should be able to disable and enable devices using CM_DisableDevNode and CM_EnableDevNode.

Brian