Usualy on models without a dipstick the following procedure is put in place.
1 Start the engine
2 Place gearbox in P (parking position)
3 Allow gearbox oil to warm up to about 60-65 celcius
4 Open the breather nozle at the top of the gearbox
5 Add about 250 ml of oil (check for exact type!)
6 Open the drain/filling port (usually on the side of gearbox), the oil will drizzle out a little bit and will just drip. This indicates that the level is OK.
If no oil spill, that means that level is too low, repat procedure till drizle visible.
Lucas
July 2009