Thanks curaga, but that is not working as I would like. What I'm hoping to be able to set up is something like this:
1) User/developer can enter 'make install' to build the app's .tcz and persistently install it just as if he or she used AppBrowser or the tce-load -iw to do so . As a result of this, the app's extension would be copied to the TCEDIR's optional folder, the extension would be added to the onboot.lst file, the app would be 'installed' (e.g. mounted) into the filesystem, the app icon would be added to the wbar, and the app would be ready to use immediately.
2) After doing the above (or installing the app previously from a repo using a conventional tools) the user/developer can enter 'make update' to re-build (maybe after changes) the app's .tcz, copy it to the TCE optional subdirectory, and also update the file contents from the .tcz into the extension's mounted parts of the filesystem so the new version is immediately available and usable. (Note, this should not cause wbar to have a duplicate!)
I guess I found it surprising that tce-load -i for a local file doesn't really persistently install the local extension (I think it just mounts it), and that there is not a straightforward way to force-refresh a persistent extension from a local copy of it.
Am I just overlooking a better way to do this stuff, or is there perhaps an opportunity to make the TCE commands a more complete and orthogonal set of functions?