I use a very small flat blade screwdriver. Looking at the open end of the terminal, you'll see a tang on the outside edge of every terminal. This tang keeps the terminal from backing out of the plastic bulkhead. Push the terminal all the way in, insert small screwdriver to bend tag flat (toward terminal), then pull terminal out.

Upon installation, simply bend that tang upward agan and insert into the proper cavity. The tang will have some spring to it, so it will keep the terminal in postion when fully seated in the bulkhead.

I bet Lisle makes a tool specifically for this, though. Check on eBay, as they do have a tool for the round terminals.