I seem to remember there was a way to set up one of your teams stacked on a door, then tell them through one command to breach and clear when you aren't near them.

The only way I've found to do this is using the picture in picture for the other team, maximize it so you control the window, then tell them to breach, then minimize the window to control myself and breach another door.

What you are referring to is using the go command or zulu command ( as it was called in Rainbow 6 I believe)

So you can give a command then tell the team to wait and then instead of using picture in picture you give the go command and the teams will all execute simutaneously the pending order.

To do this in SWAT 4 it is only in the expansion - you just old ctrl as you issue an order and the element will now wait for you to issue the initiate command for the gold element. When you do that all queued orders for all elements will execute. This is rudimentary though and you can only queue one order so it is best for doing things like a multiple entry breach.

The best thing would be to try the Elite mod which adds this feature for the whole campaign etc.