You've sold me; where do I find the specifications or examples?
For starters, you can get the current TCL/TK release via anonymous FTP from
sprite.berkeley.edu in the tcl directory. Getting the distribution of TCL and
fiddling with it is an excellent place to start.
The discussion list for safe-TCL is
secure-tcl(_at_)uunet(_dot_)uu(_dot_)net(_dot_) (There's also a
newgroup for TCL. I don't know if there's a corresponding mailing list or not.)
I don't know where the safe-TCL list archives are offhand, but they may well be
somewhere on uunet.uu.net. The last public proposal for safe-TCL appeared on
that list. You'd have to contact the authors of that proposal
nsb(_at_)thumper(_dot_)bellcore(_dot_)com) about what's happened
since then, as well as for specifics of what work has been done on public
implementation of safe-TCL. (My implementation is highly specific to the
environment and user agent on VMS.)