The ATS code uses tcl namespaces, providing its API in the "template" namespace, and using various other namespaces to hide its global variables from the rest of the interpreter.
If you want ATS to work with tcl 7.6, you could try replacing all the "variable" commands with "global", and deleting all the "namespace eval {}" commands if they're causing errors. But obviously Karl, the author of this code, designed it with tcl namespaces in mind, so you may run into some fundamental problems.
Save yourself some time by ignoring any code that isn't called by template::adp_parse, because that's the only entry point used by the cms code you're using. You probably just need to look at parse-procs.tcl and tag-procs.tcl.
