Final Fantasy Hacktics

I was wondering how I could make maps like 'Thieves Den' and 'Fort Ziekden' regular battlefields that I could encounter monsters and such on. Is such a thing possible? and if so, do you mind teaching me how. I'm assuming I can't do it with just ENTD in the patcher, as I don't see an option to do so. Just editing the characters on the maps themselves doesn't make it a regular battlefield, it just makes it so when that event happens the changes happen only then.

FFT- PSX ver.

Thanks in advance.