In the new 0.81 version I added bumpmap to all textures, except Xen (yet). It uses batch generated normalmaps with alpha channel (to make dark parts of the textures non-reflective), so the size of the arhcive is now 4.38 GB . It's not the best quality normalmaps becuase I had to reduce size to 512x512 of each one due to the big file size. I plan to generate better bigger size normalmaps when I will find a good algorithm.
Unfortunately Half-Life Source has a bug with cubemaps (env_cubemap doesn't work), so the bump will be reflecting just a simple shiny environment map. If you know how to fix it let me know and I will make an update.
Here are some screenshots (I used alternative maps from "Half-Life Resized Maps" mod which combines original plenty small sized maps into few big ones and improves lighting a bit: