Once the theme has been copied, log into HxGN EAM and navigate to the Installation Parameters screen (Administration | Security | Installation Parameters). For additional details on the style install parameter, please refer to the Style Install Parameter section of this guide.
Update the UITHEME parameter value with the name of theme you just created, click save and then log out of HxGN EAM, and then log back in. The new theme should now be active.