Digital BW, The Print

For printing on the 2400 I've put together a PS curve to match screen 
to print, essentially a luminance profile of the ABW mode.  This has 
allowed me very precise screen control by adding a layer to the file 
for viewing (which is then, of course, turned off for printing).  I'd 
like to be able able to convert the PS layer curve to an .ICC profile 
so that I can use it in the Soft Proof mode.  I know that the Color 
Management dialogue allows a custom ink gain curve, put this is not 
precise enough.  How can I take the curve (or its numbers) and make an 
ICC profile from it?  Many thanks.

Walt