!!! untested hack !!!

open 'ultralcd.cpp'
search for 'ULTIPANEL_FEEDMULTIPLY'
in this block replace all occurrences of 'feedrate_multiplier' with 'extruder_multiplier[active_extruder]'.

open 'ultralcd_implementation_hitachi_HD44780.h' for a char based or 'dogm_lcd_implementation.h' for a graphical display.
search for 'feedrate_multiplier' and replace with 'extruder_multiplier[active_extruder]'. (there should be only one)

You will still have the'FR' symbol on the screen. I have no real idea what happens if you have more then one extruder.