I know I'll need to bankswitch since Warlords was a packed 4KB game. So, I've spent the past few days getting the bankswitching framework set up. To test it I put the beginnings of a paddle driven menu screen in one bank and split the current routines amongst the other 3 banks. As you can see, the menu is quite primitive at the moment
However you can select the sole menu option and hit your fire button
to "start" the game
I've also set it up so that hitting SELECT will return you to the menu, and hitting RESET will either start the game or reset the current game. The "scores" will set to zero to show this.
Note - to try the ROM in Stella you'll need to hit TAB, select GAME PROPERTIES, the CONTROLLER tab, then set the controllers to PADDLE. Finally you'll have to reload the ROM by selecting Restart Current Game under the File menu(at least that's where the option is at under OS X, I don't know if it's different on other platforms)