On Inventoria:
(1) Open Inventoria.
(2) Options -> Other -> Advanced Settings...
(3) Check “Allow Express Invoice, Express Accounts, or Copper to synchronize with Inventoria.”
(4) Access Authentication Code: Enter a number or password that is hard for others to guess. Sometimes I use "123456" for testing.
(5) Click OK.
Leave Inventoria running.
On ExpressAccounts:
(6) Run Express Accounts.
(7) Options -> Inventory.
(8) Check “Allow Express Accounts to synchronize with Inventoria”
(9) Access Authentication Code: Enter your code again here from Inventoria
(10) IP address: Enter 127.0.0.1 if ExpressAccounts and Inventoria are running on the same computer. (Otherwise, you may need to go back to the other computer and visit <a rel="">www.whatsmyip.org</a> or use another approach to see the IP address of that computer.)
(11) Enter the port number, which is 1097 for Inventoria by default (unless you changed to something else)
(12) Location name: Click "Retrieve Locations". Then select a location from the drop-down. If you haven't changed the defaults in Inventoria, it will be "Main Warehouse".
(13) Click "Update now" to make sure it works.
(14) Click OK at the bottom of the window.