i looked at that post on onother site and ime still non the wiser, i have however found the drain plug and breather plug! but not the refill bolt thingy
If the breather plug is at the top of the gearbox (small black cap) just do it through there......
the breather is a weee white plug sat in a bolt in this case, i dont know how much ive lost so dont know how much to put back in, hence needing to get to the refill plug.
edit to say the original job was ball joint and that took about 20 mins but hours to fix the oil problem now!