Digital BW, The Print

How do I relate and convert a measured paper/ink density value back to the
0-255 scale used in PS's curves?

If I were to print a 255 step wedge out for a particular printer/paper/ink
setup I will have in front of me the tonal range (in 8 bits) of that setup.
The 0% wedge with a density of say 0.04 is off-white rather than pure white
and the 100% wedge (or 255 wedge) is also a dark dark grey rather than pure
black - let's give it a density of 1.65.  I have a compressed tonal range
versus the input values of the image on the display (with a good monitor
with great tonal range).

Furthermore, if I understand the process of printer linearization properly,
my "output space" is linearized and so there is a straight line relationship
between steps in input values and the steps in output values.  And so if the
printer is linearized properly this compression of tonal range can be
"replicated" by a curve which has the zero output level shifted up and the
255 output level lowered.  The slope of the curve is less and hence the
contrast or gamma has been lowered.  Worse yet, if, as is most commonly the
case, there is greater tonal compression at the 255 level than at the 0
level, ie we have better paper whites than we can achieve ink blacks, then
the mid-gray value has shifted lower also.  These two factors, I understand,
are why unadjusted prints print "lighter than they appear on screen" - a
common complaint.  

If I can relate my printer (paper and ink) output range, dmin and dmax, to
the 0-255 range in PS's curves then I have a more precise mechanism for
dealing with output tonal range compression and readjusting the mid grey
point (and any other points on either side of it) - I can use a curve to
compress the tonal range before it gets to the printer with much greater
control over how that compression is done (or in other words I can get away
from linearized situation that exists in the printer domain).

Thoughts?