I found a map sitting in my map directory. It was either from a very early version of Jailbreak or from an entirely seperate version of Jailbreak. Regardless, it works with JB3 so long as you keep the number of players down to about 3-4 per team. Otherwise, killed players start spawning at other spawn points, like in the other jail, or on the map, or elsewhere. Anyway, I just thought I'd donate this to the JB community...
http://twelvebaud.is-a-geek.net:25025/JB-Intrusive.zip
http://twelvebaud.is-a-geek.net:25025/JB-Intrusive.zip