KanecoPlace the .bsp in your Usermod/maps folder of SFM.
Then when you open SFM when you load a map hit the "Rescan" button. SFM will be able to see the new map.
Viaduct pro is pretty bugged in SFM and crashes constantly, afaik you're gonna need to use rc3 for SFM, it's the latest version that doesn't crash
Thanks again m8. Your advise really helps me out. Edit: i've googled around for a bit and i can only find a folder that has not even a .bsp in it