Manually Merge to HDR

I want to combine several exposures into one HDR, but I don't want to use the functions inside of Photoshop (merge to HDR) or Photomatix. I would like to combine these images manually. How is this done? My thoughts...

Three photos on different layers inside of a 32 bit project of After Effects or Photoshop (first +2EV, second 0EV, third -2EV)
- Swith the blending mode to add and adjust the overall exposure down using an adjustment layer
OR
- Adjust the opacity of all layers (100/3 = 33.3; therefore each layer would be 33.33% opaque)
OR
- Is there another blend mode that would allow me to combine these exposures?

A bit late but this may help (The whole tutorial is good) but this is specific to you:

http://www.stuckincustoms.com/2006/06/06/hdr-tutorial-part-3/



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