This is what I do/did. I had previously emptied my BTC from my main wallet. Some BCH got stuck as change when I transferred it away, so I installed Bitcoin ABC in a separate directory.
Uncheck the box that lets Armory run bitcoin core. It will find it, if it is running - as long as your firewall is not blocking it.
Keep separate directories for Bitcoin ABC data and Bitcoin Core data and copy the Armory wallet to another directory, but remove the database directory for when you use it with Bitcoin ABC.
If you want to run Bitcoin, do it with a shortcut e.g. "D:\Program Files\Bitcoin\bitcoin-qt.exe" -datadir="D:\BitcoinData" -disablewallet
When synced, run Armory with the shortcut that I mention in the previous post. Follow the directions on the first page.
Not sure if this is the easiest method, but it worked. I am using Windoze, but other OS's should have something similar.

You will probably need to export your private-keys into a different wallet to spend the other coins, as Armory only supports the original Bitcoin. If you don't to risk your Bitcoins while claiming the other fork coins, empty your wallet by sending your Bitcoins to a new wallet before importing your old keys into a not so reliable wallet.

Here are the methods I used to claim my coins after each fork:

To claim the BCH:
- Export your private keys and import them in a supported wallet such as Electron Cash (recommended);

To claim the BTG (you will need an android device):
Source: https://bitcoin.stackexchange.com/a/63227