How do you make it easy for your artists to author content for an HDR renderer? What kinds of tools should you provide, and what workflows need to change, in going from LDR to HDR?

Note that I'm not asking about the technical aspects of implementing an HDR renderer, but about best practices for creating materials and lighting in HDR. I've googled around a bit, but there doesn't seem to be much about this topic on the web. Can anyone point me to some good resources on this, or share their own experiences?

Some specific points:

• Lighting - how can lighting artists pick HDR light colors? Do they have a standard LDR color picker and then a multiplier? Is the multiplier in gamma or linear space? Maybe instead of a multiplier it's a log-luminance? Or a physical brightness level, like the number of lumens? How will they know what multiplier/luminance/brightness is "correct" for a given light?
• Materials - how can texture artists make emissive color maps, such as neon signs, TV screens, skyboxes, etc? Can you paint one as a regular LDR (8-bit-per-channel) image and apply a multiplier (or log-luminance, etc.)? Are there cases where it's necessary to actually paint HDR images? If so, how do you go about this in Photoshop (or other software)?