I haven't pulled apart my Shimano barcons yet, but I assume they are similar to the old Sun Tour barcons. You'll need to remove the lever by removing the screw on the side. That might be easier if you disconnected the cable, but maybe you don't have to. After the lever is removed, you should see an allen key fitting inside, right in the middle. This will be an expanding bolt that holds the lever in the bar. Loosen it a couple turns until the lever is loose enough to pull out.
The tape probably doesn't fit inside, but depends on the thickness of the tape. Easiest to cut the tape flush and then wind some electrical tape around the end to secure it.
Oil is good, grease is better.
2007 Peter Mooney w/S&S couplers/Terry Butterfly
1993 Bridgestone MB-3/Avocet O2 Air 40W
1980 Columbus Frame with 1970 Campy parts
1954 Raleigh 3-speed/Brooks B72