Yep, that's possible, but you'll need to write a few lines of JScript for it. The basic idea is that you need to do delta's among records - the time spent by a page is the difference between the timestamp in the END event and the timestamp in the START event. Log Parser doesn't natively support calculating differences between values in different records (so does SQL, but SQL supports inner JOINS, while Log Parser doesn't support JOIN yet).
There's a "FindSlowFilters.js" sample script in the samples folder that does just this with ISAPI filters: parses a WS03 RTM trace, calculates the delta's between the end-start events of each filter call, and finds out which filters are slow. You should be able to adapt it to ASP pages with minimal effort.