I would suggest going to NIs website (or catalog) and taking a look at the DSC toolkit (formerly marketed as BridgeVIEW). This software already does exactly what you are asking for.
Contact your local sales rep, they can give you a demo CD with a simulation on it that will surprise you. There are two simulations, one is a conveyor belt, the other is a tank that fills and empties.
If you can't afford the entire DSC toolkit, they also sell just the industrial automation picture tools. I highly recommend DSC however, as it sounds as though this is what you are doing.
The alternative to all of this is to use custom controls. This is very difficult, and since it has already been done, will be an investment of your time that far exceeds the cost of purc
hasing either of these toolkits.
Good luck.