I don't understand why you need a control to do this. You can branch the wire leading to the indicator and wire it to whatever function you'll use to manipulate the data, and then wire that manipulated data to a function writing the data back to Access.
If you want to create a sub-vi to do the manipulation or write back to Access, you can copy the indicator to the new sub-vi, right-click on it in the sub-vi, and select Change to Control. You can then place a terminal for that control on the connector for the sub-vi so you can wire to it from the calling VI.
