The values are colors according to the VDC
$selfillumtint "[<red float> <green float> <blue float>]"
Adjusts the colour of the self-illumination effect. Default value is "[1 1 1]".
Read up here-
http://developer.valvesoftware.com/wiki/$selfillum
Now on the question of creating a glow effect, your best bet might be using a particle field, as that's how VALVe achieves the glow crits have.