In the scenario editor you can access all the troops from near the middle/bottom of the screen. I assume you would have to have Immortal Fire installed.
I bought and installed Immortal Fire just to get a better trooper. I don't the see Syrcusans troops show up on the sword icon, just the set from ...

I want to design my own scenario, after visiting the actual site. I want to use the armies provided in the Immortal fire Expansion pack How do I get those troops in my do it yourself scenario?

Any techniques on creating a walled city?
Any progress on getting buildings, or were battles always ...

I agree. I enjoy trying to make a scenario, but from my onsite observations, there were always buildings that should be in the terrain mix.