Looks pretty straightforward, i think I'll give that a try.
If you follow those instructions exactly... you'll get hundreds of private keys as it includes all the "unused" ones (or what Armory thinks are unused if the wallet is not synced properly). If you've checked in Armory and know the exact addresses, you can also tick the "Address String" box and then find the specific private key(s) that you need.
Also note that you don't want to copy the "PrivBase58:" part when you are copying the private key(s)... you only want the 51 chars (starting with a "5") or the 52 chars (starting with an "K" or "L")
If you have any issues, let me know... and what wallet you're trying to import into to.