I have a torus that I would like to turn into a light.
Does anyone know if this is possible?

I don’t want to add a self illumination.
I’m trying to make a consistent light source from an object
rather than applying many spot lights around a cylinder to light it.

If you are rendering with mental ray and using Final Gather, you can make a self-illuminated material seem to cast light by checking “illuminates scene using Final Gather” in Arch & Design materials.

Other than that, I don’t know of any way to make an object cast light.  Would it be possible to use a Photometric light and set the shape to disc?  It might help if we could see an image of what you are working on.

3DS Max Design 2011 64-bit - Advantage Pack
Dell Precision T5500, Dual Six Core Xeon X5650 @ 2.67GHz, nVidia Quadro 5000, 24 GB RAM, Win 7 Enterprise 64-bit
Minneapolis, MN, USA

I would agree with Chris, these are really your only solutions. The photometric disc is probably the best solution if you’re really determined not to use an array of lights.  The Arch & Design material looks really nice and you could use a glare shader to give it a nice glow, but if you need it to cast shadows or use any environmental effects you will be out of luck.

There is a “hidden” mr shader for this, the mia_light_surface shader. In Max it is listed as Architectural: Self Illuminator. You will have to edit the architectural_max.mi file to access it.
There is some info on it in the mr.architectural.shaders.pdf, on page 104, chapter 4.3.

Yet another reason to buy a decent renderer like Final Render. It will let you turn anything into a light. Mental Ray in Max pretty much sux.