How to use unkn0wn's texture installer:
http://unkn0wn3d.tk/csgo-texture-installer/?p=doc

Basically, you choose v_awp.vtf with "Select file" in the program. Then you type "awp" in the "replaces" box and choose the one that say:

models\weapons\v_models\snip_awp\awp.vtf

Then you simply press install.

When installing w_awp.vtf, I recommend you type "w_snip" in the "replaces" box to find it faster. The one you should replace is obviously:

models\weapons\w_models\w_snip_awp\awp.vtf

Have fun!