I Want to port CoD 1 (and UO) maps to Source (Garry's mod)

Hello everyone !

I began playing Garry’s Mod not that long ago, and i quickly found it awesome.
The concept of a sandbox with a community that can always bring new content in the game is awesome.

I saw on the Steam Workshop that there are many addons (characters, weapons etc…) from many games, but when i try to download a map from a same game to put my character in it …well… i don’t find any map from this game.
So i thought “Why not porting these maps myself ? I know that Call of Duty (1) maps are based on the Quake 3 architechture and the Half-Life maps are as well, so there got to be a way to port CoD(1) maps to Garry’s Mod (/ Source engine)
I found (using google) on this page that a support for Call of duty 1 and Call of duty 2 has previously existed on GtkRadiant :

(I found this on the Gmod workshop : http://steamcommunity.com/sharedfiles/filedetails/?id=180880680&searchtext=call+of+duty )

I would like to know if there is a way to port SP and MP maps from CoD 1 to Garry’s Mod.
If you know how to do, please explain it step by step and add screenshots if you can.

Thank you for reading and answering

If you can somehow get the map file as a .map file, you can directly open it up in hammer.

Maybe.

It might be required to first save the map as a .map file or whatever, then open it in a Quake Hammer tool, and save it there as well, but mostly that should be the process.

I have some .map files that i downloaded somewhere on the internet.
So what should i do now ?
Open them in Goldsource hammer ? “Quake” Hammer ? Hammer Source ?
Do i need to configure Hammer ? Do i need FGD, WAD, gameconfig.txt files ?
and what happen after i opened the game into Hammer ?

I think someone recently used GTKRadiant to remake a BF3 map and got it into Source easily.

OK
Any link ?