Hi Chuck, and congrats on the new toy.
I have never bothered about getting the indicator perfectly perpendicular to the table. After all, you are initially just checking if readings, whatever they are, are the same or different. Unless you are very lucky, they will be different. But to find out how big the difference is, it will need to be reasonably perpendicular in the sense of being parallel to the spindle. Eyeballing it against a square sitting on the table will be good enough.
If you have an articulated holder for the indicator, you may be able to use parts of that to give you a decent circle. Arrange things for as big a sweep as you can without the plunger coming off the front or back of the table. For the LH and RH ends, you could use a bigger sweep.
Slip a bit of thin metal or card under the plunger while you are turning the spindle to move the indicator from one position to the other, so it doesn't drop down into the T slots as it goes over them and get bent as you, all oblivious, carry on turning.
Andy