I had mine like that - basically they stick a canula in a vein , flush it through with water (or saline - not sure) then put a heceptin infusion through. when i had it done it took about an hour but nowdays i think they can do it in half an hour. They then flush some more water through (i think) then unhook you an you can go home.
In my case it wasnt nearly as bad as the chemo although it can leave you feeling a bit tired. Also the infusion can feel a bit cold so it might be an idea to take a cardigan/throw with you in case you feel shivery.