How can I guarantee the w3wp process exists before turning on perfmon logging?

I have a batch script I run before our performance tests that does some pre-test setup on our server; it clears log files, starts the proper services, restores the database, sets some app settings and turns on perfmon logging.

My problem; the w3wp process we need to monitor is not always present at the time we turn on perfmon logging. It's pretty much hit-or-miss if this process is in the log. The test takes anywhere from 4 to 18 hours to complete, and I don't know until the test is done whether or not w3wp was monitored (it doesn't seem that perfmon detects new processes even though my log file is configured to monitor Process(*)), which ends up wasting a lot of time.

Is there a way to force w3wp to get loaded? Is there some command I can call just prior to starting the perfmon logs?
Or, is it possible to configure the perfmon log to monitor processes that may not exist at the time the log is started?

Solution

If you install the IIS Admin tools, you can call a command line app called TinyGet. You can pass in any page on your webserver to initialize it. This would start up the process so you can capture it.