How can I use bz2 with my FastDL server?

I’m renting a server and was wondering how I can use bz2 maps instead of bsp. The problem is that I can’t upload to the FastDL server itself, it automatically uploads whenever you upload the the maps folder or something.

Contact the GSP and ask them. If you have no access to the FastDL server then that’s your only option.
Or you could try putting the bzipped files in the maps folder and see if the FastDL script uploads that too.