Code:
lrinput var byte : frinput var byte : lroutput var byte : froutput var byte
loutput var byte : routput var byte : lrdeadband var byte : frdeadband var byte
lrdeadband = 32 : frdeadband = 32
lrmid var byte : lrmid = 128 - ( lrdeadband / 2 )
frmid var byte : frmid = 128 - ( frdeadband / 2 )
;adcin x
;adcin y

if ( lrinput > ( 128 + ( lrdeadband / 2 ) ) ) or ( lrinput < ( 128 - ( lrdeadband / 2 ) ) ) then
     lroutput = lrmid   'set output to middle value
else
     if lrinput > ( 128 + ( lrdeadband / 2 ) ) then
          lroutput = lrinput - lrdeadband
     endif
endif

if ( frinput > ( 128 + ( frdeadband / 2 ) ) ) or ( frinput < ( 128 - ( frdeadband / 2 ) ) ) then
     froutput = frmid   'set output to middle value
else
     if frinput > ( 128 + ( frdeadband / 2 ) ) then
          froutput = frinput - frdeadband
     endif
endif
After this bit o' code, left and right should have the deadband taken out, with (in this case) the mid-point of left/right being at 112, and the forward/reverse midpoint is also at 112.
Now you have to drive the H-bridge...
What do you have setup for that? Or do you have a separate controller for it or what?
Then you have to add in some code to find and/or remember the minimum and maximum values ever read for the pot's, sort of like a calibration routine for joysticks on a PC...blah blah blah...but I suppose you can keep adding tricks to the code until it gets unbearable...