Scripting Transmit to synch only .asp files

I need to synchronize a local folder with a remote site that’s rather large. I would like to script it such that only files with the .asp extension are synchronized, so that I don’t eat bandwidth and disk space with images files, etc. I am, however, only a rank novice at Applescript.

Looking at the sample scripts Transmit provides, and at Apple’s Applescript documentation, it looks as though I should be able to use the synchronize command, except, looking at the dictionary, I don’t see a way to filter by file type. I was wondering if, in more recent versions of Transmit (I have 2.6.2), there is some provision for something like a comma-separated list of allowable file types to be used with the synchronize command? If not, is there some other way to accomplish this, some way to get an If statement in there?

Model: dual 1.8 GHz G5
AppleScript: 1.9.3
Browser: Firefox 2.0.0.1
Operating System: Mac OS X (10.3.9)