Thank you all for the compliments, but this is really quite a simple setup that anyone could do with the right resources and parts.
I have replaced every pulley (including both tensioner assemblies) on my engine in the last 3 months or so. I saved all the parts. This new idler is made up of:
1/8" steel plate, cut to shape starting with the original ICM wiring harness shield as a template (you should all have this under the ICM bracket, this idler bracket replaces it).
The bolt is the original from the double idler assembly (the one with the ribbed and flat belts on it to the left of the water pump).
The spacing is made up (bolt has a shoulder that fits into the idler, but it'* long enough for TWO) by removing the center spacer that was between the idlers (remember I replaced this and it'* a spare), and putting it on the bolt first, then the idler pulley. That'* the aluminum disk you see in this pic between the bolt and pulley:
After this 'spacer', I used the OEM dust cap and then the idler. The dust cap is CRITICAL. Not only does it protect the bearing, but it also allows the bolts/washers to only contact the face of the inner race so the bearing doesn't sieze up.
The REAR dust cap (you can't see it, but it'* between the idler and the bracket) was taken from a tensioner idler (replaced unit), but I had to enlarge the hole, as it was a different diameter.
I used precision hardened washers to set the offset/spacing from there, and a plain-jane nut.
The idler pulley itself, of course, is new.