Session Drummer 2 (and 3) locates its contents via a registry key...
HKEY_LOCAL_MACHINE\SOFTWARE\Cakewalk Music Software\SessionDrummer2\Contents Folder
This defines the path where the "Contents" directory resides. Note that this is where Session Drummer looks for a directory named "Contents"...meaning...you can change the
location of the Contents directory, but you can't change it's
name.
(On my system, the Contents directory is in C:\Music\Plugins\VSTi\Cakewalk\Session Drummer 3.)
I'm thinking your best bet is to let the Hip Hop thing install where it thinks it must...and then
move it to where the registry tells Session Drummer where it
should be...inside the Contents folder...wherever it is on
your system.