Paper Trail - GTA

[TheBroadway]

Please God can someone tell me how to do this mission on the PS3. Before anyone starts going on about rockets and the like kindly bear in mind I can't get anywhere near that bit. How do I keep up with the other chopper. Do I go 'high' or low? Why is the other chopper so hard to chase? Also - can I skip it? I still seem to have a few things to do...is it integral to the story line? PLEASE HELP!