The only way that I recall hearing for DIY edge-lubing wads was to roll them through a pan with a shallow layer of melted lube. If the wads are soft enough, one can stick one or more on something like a hat pin which then serves as a handle.
As I write this, another technique came to mind, for applying a small amount of lube to a cushion wad. One forms a small groove around the circumference and hand-apply softened lube into the groove. IIRC, this was done by muzzle-loading shooters who needed a modicum of lube but wanted to minimize the mess involved with handling a more fully-covered wad with each shot.
Regards,
Joel
