After figuring how to change the hud color for my HL1 mod, I though I'd just try doing something similar for The Vorts!
All it took was a couple lines edited, all of them in the hldll's islave.cpp file.
line 744: m_pBeam[m_iBeams]->SetColor(151, 0, 255); //this will give it a nice purple color!
line 790: m_pBeam[m_iBeams]->SetColor(151, 0, 255); //I think this is for the cut revive, lets change the color anyways!
line 820: m_pBeam[m_iBeams]->SetColor(151, 0, 255); //same as the last bit of purple lightning, but this one hurts!
And voilà Think I could get it to cycle some colors too if I wanted, but I thought I'd share this for now!