Selenium and tclwebtest are not mutually exclusive, as dave's pointing out above.
"integration" in this context mostly means providing a way to access selenium test from the automated test package, so those involved in evaluating code for release can go to one place to review test results. This will also be convenient when we (hopefully) resurrect the nightly build/test cycle we had implemented about three years ago.
Rolling your own is almost always going to be easier than doing things within the toolkit framework. Go for it. As long as you don't mind your code not being accepted into the toolkit as being part of a standard release of, oh, say, .LRN for instance.
