I've been integrating Perl and TCL for about the last 6 months or so. My approach has been to use Perl to collect all configuration variables from conf files and provided arguments, Passing them to TCL by means of writing a temp TCL init file, then launching the TCL scripts. The primary online reference for TCL that I've used is the same as Kanji's, and haven't needed to purchase a book (which is unusual).

As for a comparison I find TCL slower, more syntatically demanding, but very stable to work with. It's like working on an old car, heavy and bulky but effective enough.

If your comfortable with Perl and C you'll have no problem picking up TCL in no time.