So you want to do hot seat without moving from your seat its simple with a new feature in steam

you will need

• 2 computers
  
• 1 steam account with civ 5
  
• a friend who wants to play

When you have steam set up on both computers you will need to make sure that civ 5 is fully installed on one system, easier if you chose the machine with the higher specifications as it would run smoother streaming to the lower speced machine.

When you have set it up for the first time you will need to make sure that both machines are connected, one computer must say stream and the other must say play.
click play on the machine that has the game installed on and load up in whatever dxmode you like (64 bit better to load up in 11 especially if you have a dual monitor set up)
after you have gone to the first load screen where you select what version you want to play you can use the other machine to stream the game.
when you have gotten past the cutscene and into the game you continue set up on the main device and then start playing

If you have any programs that latch onto games such as FRAPS, xsplit game caster, gamebooster or raptr the shortcuts keys will work on both machines.
the resolution on the game may look off on the streaming machine due to the compresion of the game
this is usefull for co op play with friends if you want competitive im pretty sure that you can use the same game at the same time on 2 machines although i am yet to check that