Backlash Fixes

I'm trying to find a way to get zero backlash on a 9" south bend
lathe, over a crosslide travel of about half an inch, in order to do
some high precision taper work with a sort of single motor cnc taper
attachment setup. Zero backlash is necessary because the stepper
motor will be retracting the tool in the direction of cutting force.
I should also mention that this is not a production setting - ie, it
only needs to work for about an hour at a time, and some rebuilding
between uses is acceptable.

There is no way a ballnut will fit, and I don't want to mill out the
channel in the crosslide like I did on my bigger lathe. So far I have
two ideas.

1) Install a spring that will push the tool away from the work. Using
a fairly long one, the variation in force over half an inch of travel
won't be large. The total force can be quite large, as the stepper
actually only has to retract the tool, never advance it. This seems
like a simple fix (which could be suited to longer travel with some
sort of constant force device) but I never hear of it being used.

OR

2) Buy some new screw stock, obtain a loose fitting nut, and inject
moglice (the teflon-matrix-epoxy bearing rebuilding material). I'd
use new screw material to get consistent unworn threads, sacrificial
material for any needed lapping, to be able to simply throw it away if
I don't get the release agent right, and to maybe choose an ideal
threadform. Anyone done this successfully? What would the ideal
threadform for moglice be?

Thanks for any ideas,

Chris Stratton
ccs@...