Umm. NO DON'T DO THAT. unless of course you don't mind spending hours downloading the content. Here is a solution that may work, but keep in mind that it is form my days of HL1 mapping so I'm not sure it still applies.

The .RAD file is simply a text document (with .rad instead of .txt at the end) that lists the textures you want to emit light and the subsequent values for that light. For example, a typical entry would appear as follows:

Texturename 128 255 255 200

The values following your texture name are the numeric specifications of the light you want that texture to emit in RGB format. Hence, the first number is for red, the second for green and the thrid is for blue. the fourth and final number is the luminance value (how bright the light will be). the RGB values must be integers from 0-255. The luminance field can take on any integral value.

Once you have your text file with at least one entry, name it "mapname.rad" and place it in the same folder as the map you are going to compile. any entries in the mapname.rad file will override those that exist in the standard lights.rad file.

Compile and see if it works!

(it's also worth pointing out that the *actual* lights.rad file is stored inside your Source SDK .GCF, extract this and edit it rather than creating a new one!- Lep.)