Quick and dirty:
L DW#16#FFFF
L Dint
<D
JC err
T Int
err: NOP 0 // set error bit here if you need any
Something like that should do the trick. (I hope) But just remember, when you transfer to say MW10, you should be carefull as the data in MW8 will be erased. (transferred 32 bits and such.....)