I was looking for a way to make this easier. I wanted a tool that I could use to point to a word in my viewer, and it would take me to the right line in the source file. Thus, this tip came to life.
- There's a package (that came with tetex) called pdfsync. This generates a lookup file.
- The PDFView viewer knows how to read this file, and allows running a custom script with the filename and line of code (set in preferences).
- I wrote a small AppleScript that talks to an open instance of vim (and launches it if it is closed), placing the cursor on the right place.
[robg adds: I haven't tested this script, and the links to the various sites are mine, so blame me for any errors in direction!]

