Uh I don't think you want to use a pry bar on a 5mm allen bolt.
I got mine out by sawing a 5mm allen wrench off about 1/2 in length. You can then insert the small straight allen wrench into the allen bolt and drive it with a 1/4 ratchet (with a 5mm bit and a univeral joint)
Warning: getting it out is real easy compared with reinstalling the bolt once its out.
W124's and V8's are a bad combination for the people that have to work on them. Of course they are great fun for the people that do the driving...
Best of luck - Tim