Here's the pain...
Imagine you've tweaked a custom curves adjustment to do some exotic color grading. You've got 5 points on the red channel, 4 points on the green channel, and 5 points on the blue channel, and saved as a curves preset.
If you put that in an action, that's 14 points to re-enter by hand. A channel mixer adjustment would have 9 values to enter. A Hue Sat could have up to 18 values. A selective color adjustment could have 36 values.
Since posting here, I've had an e-mail exchange with a friend. She gave me this tip:
After you load any adjustment layer preset, if you change any one value, the action recorder will record all the specific values with no reference to the preset.
In the case of a curves adjustment, simply adding a "do nothing" point to the composite curve will cause all points to be recorded, with no reference to the preset.
With other adjustment layers, there is no way to add a "do nothing" adjustment, so my friend says this:
Before recording the action, load your preset, change just one of the adjustments, and save that as a new "temporary" preset. Then, when recording your action, load the temporary preset, and change the one adjustment back to what it should be. You only have to remember one value and make one change.
In both cases the action will be recorded with all adjustments and no reference to presets. Sounds like a good plan. If anybody has a better way (to avoid making and cleaning up temporary presets) I'd love to hear it.