Well, as a final year B.Tech in instrumentation and electronics, you should be able to do this (at least in general).
Start by looking at the datasheet for the sensor:
http://datasheets.maxim-ic.com/en/ds/DS1620.pdf
Clearly, this is a digital device and doesn't require you to sample an analog voltage via your ADC (Analog to Digital Converter). It also tells you that you'll need to use their 3-Wire Communications Protocol, using Reset, Data (Bidirectional) and Clock. Data is bidirectional, which means you'll need to use the same pin (on your 8051) to transmit and receive data.
Now, put the 8051 and the DS1620 on a breadboard, wire them up, and try to get them communicating with one another. You'll need the datasheet for the 89c52:
http://www.atmel.com/dyn/resources/prod_documents/doc0313.pdf
If you have specific questions, we can try to help you through them, but we can't do your task for you!