There's a couple pictures of the taping you can do on your hands at
http://gymnasticscoaching.com/?p=2110 that we're talking about here, for under your grips. This one shows the tape being around just the middle finger; you can also do it around the middle and ring finger, to get a wider surface area more easily - I like the 2-fingers way better, it's comfortable:
Here's one way how to do it, using the sports tape (Tape-O sells good sports tape:
http://www.gymchat.com/listings/details.php?listing=26 , good pricing for a box).
-Unroll the tape roll and rip off the amount of tape that is enough to go from your wrist, around your finger, and back to your wrist again - if your coach is doing it, he/she will probably stick the end of the tape on your wrist first, and then use one hand to hold down the tape on your wrist while using his/her other hand to roll-out the tape, and then wrap it around your finger and put it back to your wrist, then rip the tape off, to have the correct amount of tape ripped off easily - if you're taping your own hands, it's easier to rip the tape off from the roll, then take the strip of tape and stick one end to your wrist, bring it to your finger, wrap it around the middle of ring finger (whichever you would like first), then bring the other end of the tape back to your wrist.
-Then repeat it for your other finger - middle or ring finger - or if you would like wrap both around your middle finger - but it's easier to get the wider suface area with wrapping the tape around the middle finger and ring finger, rather than just the middle finger, and it's really comfortable.
-After you're done with these 2 strips of tape, you rip off another piece of tape to go around your wrist to keep these strips of tape in place - again, you can either rip off the tape from the roll, or your coach can place the end of the tape to your wrist, hold it down with one hand on your wrist while rolling out the tape with his/her other hand, and then wrap one layer around your wrist to hold the 2 strips of tape in place. If you also get rips around your wrist sometimes, from the grips sliding to the side sometimes, you could also rip some small pieces of tape (like maybe about 2 inches long or something), and place it going from your wrist to the side of your hand where you get those kind of rips.
-After you're done with bars, take the tape from your wrist off, and you can keep the 2 strips of tape that are now stuck together kind of like a bars grip - when you reuse them, just put your fingers back into the tape grips holes, and tape the end of them on your wrists again.
Easy! and great! you can do a lot more bars like this, especially if you rip really fast!!