Like Henrik said, the formula is really subtracting 4000 from a WORD. So here's the way I tackled it:

Code:
wCalc   VAR WORD
G3T     VAR wCalc[0]
G4T     VAR wCalc[1]
IF wCalc <4000 THEN     'Number will be negative
    DUMMY =MULT*(wCalc+B2)
    MG2_NM = DIV32 100
    MG2_NM=10000-MG2_NM
    LCDOUT $FE, POS4-1,"-"
ELSE                    'Number will be positive or 0
    Dummy = MULT*(wCalc-B2)
    MG2_NM = DIV32 100
    LCDOUT $FE,POS4-1," "
ENDIF
IF MG2_NM < 100  THEN
    LCDOUT "  "
ELSEIF  MG2_NM < 1000  THEN
    LCDOUT " "
ENDIF
LCDOUT DEC MG2_NM/10,".",DEC MG2_NM//10