Center TA discs without tools for gearbox installation?

[Powerpoint]

The Swedish manual for mounting the TA [IH475] in the gearbox shows that I should lock the discs using two tools, one I guess helps to center internally, then there are springs that probably locks the discs in the correct position when you insert it and meet the gear in the gearbox.

These tools probably don't exist today. I have a few alternative ideas, but I think most people might just use their hand to center the discs as they go while you slowly insert the TA.

How would you have done it?

Thanks