I'm sure it was Steve Animal who had the rig. It was based on a bearing puller but I haven't seen the thread for years
If there is a way you could fiddle a nut onto a piece of threaded bar between the alloy plates you could tighten a bearing puller onto the outside and use it to push the bar through against the other plate
I'm sure that's how it worked but I have slept, drunk a lot and fell off my bike quite a few times since I read it last or attempted to fix a pair myself.......