Steam?

[Outlawed]

Is there anything I need to do in order to play the mod while running RTW on steam?
What do I need to do in order to play the Vanilla and the mod?

[Peppe]

Works fine. Use the installer that installs as a mod folder and the vanilla game won't be affected. In the installer you have to manually select the path to rome total war. Something like steam -> steamapps -> common -> rome total war gold.

I think it makes a shortcut to the BI.exe. You can do a couple things to make a working shortcut:
Replace part of the target box to the total war exe to use the same target as your vanilla game (but leave -nm -show_err -mod:ExRM). This will correctly launch the mod through through steam modified exe of the game.
Now, I wanted to use the mod using the Barbarian Invasion EXE, which is not possible through steam's DRM (BI does not have its own SteamID). There are a couple fixes for this. I saw someone wrote a little Batch script to swap some files and i think registry entries around to launch steam's BI through a shortcut. I chose the easy way out and used a DRM free version of the BI EXE to load mods.

[Caesar Augustus]

I don't know that there are any special requirements, but I'm sure somebody will correct me if I'm wrong.

I think you'll have a separate shortcut for EXRM and for Vanilla RTW, so as long as you use those shortcuts you should be ok. If you don't have a separate shortcut, look for a thread I started called something along the lines of "Aye Carumba, Big Problem!", one of the posts in reply to the difficulties I was encountering gives instructions for making a shortcut use the EXRM files rather than the RTW files. I'd imagine the thread is probably somewhere on page 2 or page 3.

Hope this helps!

Keep truckin'

[Caleb ConDoin]

There is actually a much easier way, download in the folder Peppe told, you to then go to RTW BI or Gold whatever you have go to properties, launch options, and then put-mod:ExRm in the line. If you ever want to play vanilla all you have to do is go to luanch options and clear it.

[Quinn Inuit]

Good thread, guys. I think I'll add a link to this to the main post.