Ok the Fresnel ramp worked as expected...on the white part of the light. I had to change how I textured the lamps to take into account the Fresnel transparency, but on doing so, the red part of the light now has a white halo around it. My previous method of doing the lamps, using One/One had no such issue, but of course means no Fresnel ramp. I've spent about an hour checking the texture alpha channel for any abnormalities, the texture is DXT5 and there's a gradient fade out, but instead of going red->transparent, it goes red->white->transparent.
If anyone knows how to get rid of this white bit that'd be great, otherwise my box method with One/One will have to do.
EDIT: The box idea gives the same result of the "flash". Need to get the transparencies working.
EDIT2: Got the transparencies working. It was down to the Bloom settings in GMAX. So for my records and to help anyone else, this is for daytime and night-time lighting:
Diffuse and Self-Illumination - choose textures
Specular: White colour
Specular Level: 85
FresnelRamp: Choose texture and assign to Diffuse
Blend diffuse by diffuse alpha
Untick Allow Bloom and tick Allow emissive bloom
Set Default Transparent
Emissive Mode: Additive
Tick No shadow
All other options: defaults
The texture itself needs to be 2-bit alpha however (i.e. black or white). I've not yet got it working with 8-bit alpha as it still produces a white halo around the colour, but not to the extent with Bloom enabled. It also cannot be double sided!