The real problem with current monitoring , is not only you have to disconnect the two point's from the circut (and monitor between them) , is that you have to do that with minimum effect on circuit , which means , resistance of 8051 ->0 ohm.

well try this :put a NPN trans as follows :
base=Point 1
Collector=Vcc + Rx
Emitter=Point 2 + 1k ohm R to ground !
on the 1k ohm R , do an amplify of 1 (with 741) , so that infulance on circuit will be unaffected !
on 741 exit , now you have Current*1000.
all you have to do now is plan your self a 8/4 bit a/d (depend's on resoulotion you want for your self) , all the rest is on the 8051 program.
good luck.