Good news. It is a pretty simple layout.
For future reference, in most cases relocating files for most synths does not need a registry entry, it may be accomplished with the DOS mklink command using the /d or /j switch. In the above case, after creating the "d:\Samples&Synths\Dimension Pro\Multisamples" directory, the DOS command
mklink /j "c:\Program Files\Cakewalk\Dimension Pro\Multisamples" "d:\Samples&Synths\Dimension Pro\Multisamples" would create a junction in the "C:\Program Files\Cakewalk\Dimension Pro" directory called Multisamples. The junction would point to the "d:\Samples&Synths\Dimension Pro\Multisamples". Any time an installer wrote to the "C:\Program Files\Cakewalk\Dimension Pro\Multisamples" it would actually be updating "d:\Samples&Synths\Dimension Pro\Multisamples". Any time DimPro read sfz or samples from "C:\Program Files\Cakewalk\Dimension Pro\Multisamples", it would actually be reading them from "d:\Samples&Synths\Dimension Pro\Multisamples".