This works analogous to how such things were done on System 7: First, use one of the FindFolder() APIs to get an FSRef to the "Preference Panes" folder. In this folder, every preference pane has a corresponding file, which you can open by simply handing it to LSOpenFSRef().
If you get an error like "warning: could not use precompiled header '/System/Library/Frameworks/Carbon.framework/Headers/Carbon.p', because:
warning: 'OpenScripting/OpenScripting.h' has different date than in precomp", then very likely your precompiled headers are out of sync with the actual headers and the installed software. This can happen since some of Apple's installers only update the software, but neglect precompiled headers.
But fear not, the fix is easy. Just head to your friendly neighborhood Terminal.app and enter "sudo fixPrecomps -force" and MacOS X will try to update all precompiled headers.