I made due with a loaner balljoint press from from a parts store. The big requirement was that you need a very short die that fits the outside diameter of the balljoint with the boot removed, and I had to use my impact set on high for quite a while to get it to slide in. The die needs to be roughly 1/2" long, then the set will have some stepped spacers that have a hole in them for the threads of the balljoint to fit through. It wasn't a particularly fun job. You could probably find a metal shop with the right diameter tubing who is willing to cut you the short spacer. (The one in my kit had a bit of a bevel cut to the spacer, which meant I had to rotate the spacer a few times to get it pressed in evenly)

The cutout tubing piece that DeliveryValve and charmalu show seems like a nice solution too.