From what I understand, ball joint grease has a high shear handling property and is designed for high pressures, it is a bit gloopier than normal grease. 80g tube on eBay for £4 incl p&p
http://www.ebay.co.uk/itm/370988592777 . It would be easier to remove the wishbone, that's not the time consuming part, greasing up and getting the spring clip on took the longest and I can imagine that would be twice as difficult in situ. Don't worry too much about your driveshaft, it won't fall out on its own, just don't pull it more than an inch away from the car!
