OK, took a first shot at running a BOINC extension on TCL.
Untarred the BOINC extension files and moved them into /tce/optional OK. After that:
Initially ran tce-load -i boinc in a default terminal (home/tc). This created several files in the home/tc folder. Then ran boinc_client. Client appeared to initialize correctly, however it says no projects assigned to BOINC. This is to be expected. Client message said to go the BOINC website for instructions on attaching projects.
In the past I've used boincmgr, so I terminated the client (CTRL-C) and tried boincmgr. boincmgr started but terminal showed messages "execvp(/home/tc/boinc, --redirectio, --launched_by_manager) failed with error 13!". Manager panel showed "Unable to connect to core client".
Thought there might be a folder issue, so created a boinc directory under home/tc and moved BOINC files there. Re-ran boincmgr and got the same results.
I'll do some research and see if I can resolve this. I think the extension is probably OK but there's something wrong with how I'm trying to run it.