Thanks for the responses, folks, and I realize I could've been clearer in one aspect of my problem description. In stating that "SC will not permit me to install to a directory of my choosing," I was referring to the Stardock Central program itself. From the get-go, Ive run SC with the "Silently install new software" item unchecked, and've had no problem installing Object Desktop stuff.
I've got a sizable history of becoming peevish when a program's set-up routine won't allow me to install the pgm where I want....<shrugs>