I update my Panasonic through the internet, I guess that's not an option for you?
If it's similar to these instructions,
SC-BTT370/770 Firmware Download (North America) | Download | Blu-ray Disc Player/Recorder | Digital AV | Consumer Products | Support | Panasonic Global
You need to make it an ISO file first.
The Official ImgBurn Website will do that, First, in easy mode, select Create image file from Files/Folders,
Then select your source (put the PANA_DVD.FRM in an empty folder) and destination folders, and under the options tab change the file type to ISO9660 (Stated in the instructions from Panasonic)
It will ask you if you just want the contents of the folder in the image file, yes.
It only takes a few seconds to create the ISO, then you can burn that to a CD with imgburn or windows.