Source Engine maps to Quake3 engine

Getting started:
Open BSPSource with bspsrc.bat

Click on Add , then select and open the .bsp map (I'm using the CSGO cs_italy.bsp)

Go to the Other tab and select the game the .bsp is made for at "BSP format" and Decompile.

Select where you want the .vmf to be created, give it a name and press Save

Once the last line is "[info] Processed 1 file(s) in x seconds" , you can close BSPSource

At this point, I suggest making a copy of the .vmf you created, in my case cs_italy_d.vmf because the texture information will be lost so everything becomes caulk, even the tools brushes (and skybox) which
is anoying to retexture as you can't see what is what.
So one .vmf will be the tools brushes + skybox, and one will be the world brushes. You don't have to do this though if you don't want the tool brushes and skybox seperate.

Next you need to open SourceSDK's Hammer or CSGO's Hammer, I prefer CSGO's but they're basicly the same. I'm just having issues with the config of SourceSDK's and not willing to fix it

Open the .vmf in Hammer by going to File/Open, then at VisGroups/Auto (a tab at the right bottom) and untick "Auto" first so everything gets hidden, then tick what you want to remove.

Lets remove the Sky and Tool brushes. Do this by ticking Sky (under World Geometry) and Tool Brushes. These will show up now. Now go to Edit/Select All and then Edit/Delete.

Now you can tick the "Auto" back on so everything is visible again. Notice that Sky and Tool Brushes isn't in the list anymore?

Now let's Save the map again by going to File/Save and close Hammer

Almost there

Open the saved .vmf with Crafty and go to File/Export and save the map as "MAP Files (*.map)

Next, open hlq3map and click on input and browse to the .map you just created. Then click on Output and choose a location and name and click on Save, then on Convert
NOTE: Don't use the same name as the other .map

Map processed Successfully !

EDIT - 13/03/2016 - I found out that exporting VisGroups seperatly in Hammer works much better as you can edit each entitytype much easier