Mass-convert TIFFs to PDF

I work for a water utility company and we have 1000's of plans scanned to TIFF, some very long (up to 15m) In order to reduce printing costs, these have to beconverted to PDF for easier viewing.

I have found that Bentley Viewer and Microstation v8i are very efficient PDF creators. With the right pltcfg, they produce compact and efficient PDFs from TIFFs, longer than 5m.

After opening the TIFF in either of the above programs, I proceed as follows:

- select the TIFF
- place a fence around the border
- print the fence towards a certain .pltcfg-file
I would like to be able to do that with the complete database of all my plans. I need a script to execute and drive MS, because viewer has no scrpting ability.