There's a new tool called QTR StepWedge Tool. It's a Photoshop script
that can be used with Photoshop CS3 or CS4 on Mac or Windows.
It involves calibration with a know source, then reading printed stepwedges
and saving the data to a text file. Data can be used for linearizing
or for ICC profile creation.
See the QTR download page at:
http://www.quadtonerip.com/html/QTRdownload.html
Roy Harrington