Ok, you have entered the submod name. In the same menu, you can select the Hotseat campaign manually now:
You have to click on the "select a faction". You should be able to choose between three things now:
Multiplayer, Custom/Historical Battles, and Hotseat.
Select Hotseat, press ok.
I have no intention to be killed off early. And I am pretty sure my opening moves will surprise everyone - I also already have a plan how to deal with Hannibal ...
I think the Roman Empire will be around for quite some time ...