I don't think a symlink for tdom.tcl is either
necessary or desirable and package require is all you
need to do.
Here is what the README.AOL says in tdom 0.7.8:
For AOLserver 4.x:
This version supports standard Tcl "pacakge require" mechanism
so you can just:
make install
and it will install the library in the proper place. All you
need to do then is to use "ns_eval package require tdom" to
load the library and register it for every connection thread.
You should add this command to some of the Tcl startup files
in modules/tcl, so it loads the library on server startup.
I would prefer the package require in 0-acs-init.tcl so we
can make it more transparent what it going in and refrain from twiddling a default aolserver install.