I recently aquired a Pakon F-135 35mm negative scanner. It's an ancient but wonderful way to quickly scan 35mm film without a flatbed scanner. Before I bought it, I searched around the internet for the installation software. All the information I saw recommended joining Facebook and asking the Pakon F-135 group on there for it. Facebook sucks so that wasn't an option for me.
Please use the link below to download a copy of the software I received with my scanner. I can confirm it works 100% with the Pakon F-135.
Download the firmware here: https://www.amazon.com/clouddrive/share/ydeHLORP743ueHyfIfzsqFAwhsrZpTdLRly0ZIYzcIP
Edit - 8/27/2019 - There is a nice GitHub repository by plonsker with this software and a bunch of other goodies for more advanced computery people. I saw this after I posted and wanted to list it as a resource.