A friend sent me his recipe for a very nice effect. However, he uses CS2 while I use The Gimp. Can someone help me translate these into the best Gimp commands?

Note, there was no step 1 apparently.

2) convert to grayscale 3) bring up the brightness just a bit. 4) convert to duotone
5) select black as your primary and then select whatever shade you want as your secondary.
6) once the duotone has been applied, convert the image back to an RGB image

I have the "script_fu_Eg_DuotoneSimulation" by Martin Egger (12.07.2005), but I am not sure what settings to use. I've combined 2 through 6 because the script wants an RGB image for the DuotoneSimulation. Should I desaturate (remaining as an RGB image) or convert to grayscale mode and then back to RGB?

Step 5 is the most puzzling. Primary -- huh?

13) flatten the image again. ...
19) merge the visible layers then create a another duplicate layer,

I've skipped a bunch of obvious steps involving blurring and inverting and layer mode-ing, etc.

Am I right in assuming that if there are no invisible layers, that "flatten the image" and "merge the visible layers" are the same thing? Since my friend never talks about an invisible layer, I guess I ought to ask if he skipped telling me something, huh.

22) run "Unsharp mask" - amount = 20% , radius = 50 pixels, threshold = 0

Gimp's amount is a decimal. Is PS's 20% equal to 0.20?

Any help is appreciated.

Dave