Often times I end up having to go through my mta logs (found at 'C:\Program Files (x86)\MTA San Andreas 1.5\MTA\logs') in order to get the chat between a couple of people. Going through the logs manually can be a pain so I've written a tool to do this for you.
Simply paste your log file on the left, enter the users in the middle seperated by enters, and click convert. The tool will only put the lines with those names in it on the right.
This does mean if someone else typed the person's name it will still be output.
Download it here