Hello Michael,
First of all, please note that you can work with the Test Log only when a test is running.
To work with the "Log" runtime object, you need to get a reference to this object first.
This can be done either by using the Log field of the Connect class provided by the
Connected Applications modules, or you can use the
GetObjectByName method of the Integration object: TCObj.Integration.GetObjectByName("Log")
The links are to the TestComplete 8 Help system, so there may be differences - check the same topics in your local copy of TestComplete 7 Help system.
I hope this helps!