Here's a (very) small tool I wrote that generates a custom client DLL for HL1 that turns the HUD the color you specify. Useful for minimods where you just wanna change the HUD color without having to poke around in the SDK.
The DLL itself is compiled from the latest version of the SDK (2.3), with the only modifications made detailed in this tutorial (so obviously, credits for the color changing code go to m0p).
C source code is included.
Download here (476kb)