Not sure, but maybe you can just change 1-line.

Code:
'---[INT - interrupt handler]---------------------------------------------------
ToggleLED1:
   cnt = cnt +1
   cntb = cnt * 20 ; could be * 1000
   meter = DIV32 f0 
   If meter = x Then  
     meter = 0
     km = km + 1
     cnt = 0
   Endif
@ INT_RETURN
Depends on what f0 and x are.