If the o rings need replacing , and by the sound of it , they do ? You will need to pull the throttle bodies before you can lift the oil tank ! It's not a difficult job , just take your time and be meticulous !
Whilst the throttle bodies are free , it's a good time to check all linkages are clean and lubricated , you shouldn't need to unplug anything , just lift the bodies and tie them up out of the way !
There are 3 o rings for the oil tank spigots , the middle sump drain bolt drains the oil tank , so no need to drop all the oil from the bike . Disconnect the battery + terminal , this will prevent you throwing any codes if you should disconnect any plugs whilst removing the throttle bodies . The oil tank can be stubborn , as long as you have removed both bolts from the top , it will lift off eventually ! Good luck .