Here is a screen shot of the tool and the procedure for automatic transmission removal and install. The tool goes to the starter hole and holds the converter in place. It probably bolts to the converter threaded hole and mounts on the two starter bolt hole. You can make it out of a plain steel flat bar.
To me, as long as the torque converter is inserted into the transmission properly and maintained in that position during the install, and not forcing the bellhousing into the engine using the bolts, you will be fine.
