Are there SatNav/GPS navigation units that can be programmed using, say, memory stick or memory card similar to the old "sneaker net" system of old. Or if one prefers like military aircraft mission planning.

I would like to be able to program the staff's customer directions into units without having to sit in the vehicle or take the units up to the office.

Is it enough for your staff to have the desired destination(s) or must they have a special route?

If they only need the destinations, can't you simply hand out the co-ordinates on paper for the staff to enter in the GPS?

Garmins can read destinations and routes from a memory card but unless it is many destinations it is just as simple to type in the co-ordinates.