Dave posted a reply to the same thread where he tells us that he also couldn't find a TCL version so he wrote a Korn Shell script to parse the listener.log file. He says he has not had time to modify the script to deal with the listener being down for an extended time and a few other bits. Dave kindly included the source code for his KSH log parser.
This is a useful post that is worth reading and also to get the source code. I have not tried it yet purely due to time constraints.