Say they're available for use in Berg-5s and I'm in for a few!
I don't think it can be done. There just isn't enough room in the nose cone of a B-5.
Here's a pic of the B-5 hockey stick. When you pull it into R, 2nd, or 4th, the shaft of the hockey stick is burried in the bushing of the nose cone within a couple of mm from where the ground dia ends at the corner.
Then, look at the outside of the heel. You can just see how it has a flat ground on it so it will clear the special nut on the mainshaft. The reason Gene went with his custom design nut instead of using the stock hex nut was for clearance with the hockey stick when in 1st, 3rd or 5th. Things are really close in there.
Note the TIG weld on the inside of the corner to add strength that was removed by grinding on the heel.