Hi Henry,
I just tested this and it appears that running the TFX installer into a temp folder when Tongass Fjords is already installed in FSX doesn't create a complete folder tree; the FSAddon folder is created with the Tongass_Fjords subfolders but the other required folders -- Effects, Scenery/World/, SimObjects, and Sound -- are not. Presumably, the installer spots the existing FSX registry entry and places those folder contents in the actual FSX location. It also means that the custom terrain.cfg entries aren't added and, probably, the TFX configurator won't access the temp folder's files either.
Two "hacks" I can think of:
1. use a FSX registry tool (Google for it) to temporarily direct the FSX-SE registry path to the temp folder. For that to work you need to also place a copy of the FSX-SE "fsx.exe" file as well as the FSX-SE "terrain.cfg" file into the temp folder. Then run the installer into the temp folder.
2. use the file list provided in the first post in this thread --
http://fssupport.com/fsaddonforum/index.php?topic=34.0 -- to manually copy all TFX files and folders to your FSX-SE installation. Then manually add the two TFX entries to the scenery library menu and the block of TFX entries (also attached to that thread) into your FSX-SE terrain.cfg file.
Cheers, Holger