Set the IE Integration Flag

To enable IE integration you first have to set a configuration flag that enables this functionality in the browser.

Use the following URL to open the settings page:

edge://flags/#edge-internet-explorer-integration

and select

• Enable IE Integration - IE mode

Here's what it should look like:

Use Experimental Startup Command Line

Since this feature is still a preview feature you also need to explicitly specify a command line option to enable the IE integration. You can create a separate shortcut for the specific command line:

 "C:\Program Files (x86)\Microsoft\Edge Dev\Application\msedge.exe" --ie-mode-test