Yes it is possible !
Your Microcontroller connection with your RAM have to :
__
PSEN --| _____ to RD pin of ext. RAM
RD --|__/
AND Gate

After you write to external RAM, You have to jump to external RAM using command Ljmp XXXXh (not jmp, and this command, you have to put it in the last of your program, it doesn't work if you put it in the middle of your program, I tried this before)