Here's some sites that explain the procedure:
http://www.endowsec.com/pated/epdlv27.htm
http://www.niddk.nih.gov/health/digest/pubs/liverbiopsy/liverbiopsy.htm
Here's a site where you can see a short (online) video of the procedure:
http://www.filmedical.org/vefilm2.htm
I had a liver biopsy. I did not know what to expect. The doctor gave me a numbing shot in my side. I jumped but the novacaine kicked in immediately. I did not feel anything after that. They used a sonogram to find the best spot. The doctor took out a fine needle. I heard him click it a couple of times, but I did not care because I could feel nothing.
I layed on my side for 2 hours and then they sent me home. I spent 1 day in bed. You do want to stay in bed for a day afterwards. The biopsy was nothing. I feel going to the dentist is 100% worse. Good luck.