Rapture Pro uses registry key SampleDataDir in
HKEY_LOCAL_MACHINE\SOFTWARE\Cakewalk Music Software. The default value for this key is "C:\Cakewalk Content\Cakewalk Sample Data." There is a "Rapture Pro" folder here containing "LFO Waveforms", Multisamples and Tunings.
I believe the new installer permits reseting the value for SampleDataDir. I am not sure it will move the existing content so you would have to copy the rest of the expansion packs by hand or re-install them.
Another way is directly edit the registry and modify SampleDataDir
Or use mklink and create a directory junction for the folder being moved. This could be Rapture Pro or just the Multisamples folder under it. There are numerous examples of moving folders with mklink. A Google search using
site:forum.cakewalk.com scook mklinkshould bring up quite a few threads describing the process. If you have a specific source and target you need help with, I can give you the exact syntax for the command.