Photoshop :: Automated 2 Color Separations

I have a very large number of 4-color TIFFs that I need converted to 2-color PSD or DCS files. Before I do a whole lot of banging my head against the wall — or heavens forbid trying to write my own script from scratch — I'd like to know if it's feasible.
 
First, I'm not new to this. I don't need instructions on how to create 2-color DCS files from 3- or 4-color art. I do it quite often. Only I do it manually (using different methods, depending on the art).
 
What I have are hand-drawn illustrations, mostly black line with blue tints. The problem is they're 4-color. The colors are consistent — I have the same 4 tints or shades of blue plus black (or 3 tints of blue and one blue/black mix + black). I have no issues using grayscale + levels to generate the spot color channels, or Select Color Range and different percentage fills in those channels.
 
What I have is about a thousand of them — yes, literally 1,000 images — and I need them done as soon as possible. I don't relish the idea of going through all of them with the same operation, not when it can be automated.
 
So that's my question — can it be automated? What I understand is this is primarily a process that requires human intervention — a human brain that can decide "this, not that." Can I create an Action that says (for example):
 
set theColorRange to 67, 32, 23, 6
select theColorRange
fill channel Pantone Black 4 U 40%
fill channel Pantone Process Blue 100%
 
set theColorRange to 45, 15, 15, 0
etc...
 
(PS 5.1, Mac OS 10.5)