Just re-read your post...Doh
The way to remove the top nut witout the tool is just to find a flat piece of bar (i used a steel rule) and it can locate in the slot in the nut, and then just twist. The nut should only just be done up...its torqued to a very low value (ie 20Nm) and then actually losened 1/4 of a turn. Its supposed to be just tight enough to hold the steering bearing together but not pressure them.