You need to load the correct .WADs in Hammer. They are:
cstrike.wad (from counter-strike)
cs_bdog.wad (from counter-strike)
liquids.wad (from half-life)
cs_office.wad (from counter-strike)
(I found this out by opening the .map file in Notepad, it's right at the top.)
You need to use Textract to extract the textures from the .BSP. I'm not sure which ones are in there, maybe all the ones you need or maybe just the ones that I made.
1) BSP file, awp_snowsk337.bsp
2) Textract program --> http://www.superjer.com/files/textract.zip
3) Put them in the same folder
4) Open a command window there
5) Type: textract awp_snowsk337.bsp snowsk337.wad
6) Then use your fresh new .wad
Hope this helps.