Ok, just took a look at the scenarios, and they are great!

I have a question on how to mod those scenarios so I can play them multiplayer with my friends, especially the ww2 one.

Also, I try out the civ defense scenario. By the time I get to round 6, each turn just are too fast, because the time limit stays like 30 sec (or 20 something). Is there anyway to expand the duration of my turn? Or maybe easier, simply take out the time limit.

I am pretty sure you can already play RTW, the WW2 scenario multiplayer, but if I'm wrong, hop on over the Dale's forum to get the details.
http://forums.civfanatics.com/forumdisplay.php?f=265

MP will be activated in add-on pack 1. It's not activated in the release version. :)