Hello Murdock,
thank you for the repy. The code in your first posts make some sence with register writing, but when I opened the library, the code is out of my league 
Found some info in arduino site about bit math and port manipulation, and will try studying that. thanx for the reference.
EDIT:
Rebuild the circuit again, and got the chip working. might need new prototyping board 
Getting stable 16 bit, 1000 Hz results at tmb 8 and dr 77. there is quite a bit of noise though
I wonder if anyone could suggest any cicuits for unipolar single ended sensors input to this differential adc? should I just simply ground the inverting pin? or maybe someone has tried and tested op-amp circuit (i am novice with op-amps).