Joined: Jan 2010
Posts: 9,813
Likes: 1,790
From: Northern California
Bikes: Cheltenham-Pedersen racer, Boulder F/S Paris-Roubaix, Varsity racer, '52 Christophe, '62 Continental, '92 Merckx, '75 Limongi, '76 Presto, '72 Gitane SC, '71 Schwinn SS, etc.
Are you needing to remove the cups in order to replace them with normal parts?
If so, you could use a piece of 1/4" steel flat stock to turn the cups out after cutting or grinding opposing notches adjacent to the splined hole.
A very large adjustable wrench, pipe wrench or bench vise might then be used to apply torque to the flat stock removal tool.
I believe that the needed tool is usually not hollow like common freewheel tools, which makes identifying one a little easier.