You have it all already. The only 16 bit regsiter in an 8052 is the DPTR, move a 16 bit address into that, say MOVX @DPTR,A and the accumulator contents get moved to the location pointed to by the DPTR.

How do you set the DPTR ?
Either directly as MOV DPTR,#0FFFEH
or
MOV DPH,#0FFh
MOV DPL,#0FEh

Since DPH (DPTR high byte) and DPL (DPTR low byte are 8 bit registers, you can (witrh care) manipulate 16 bit numbers in your code.

Steve