If you have already made an iso image:
When you boot the RecoverEDGE image, at the boot: prompt, don't press [Enter]
Then press [Enter]
RecoverEDGE will boot to the main menu.
If you have not yet made an iso image:
In RecoverEDGE go to the Configure Menu
select BOOT IMAGE, change the "Include Following Boot String Types:" field to include "wd" (not "wd=").
The resulting line should look like this:
Include Following Boot String Types: ct= hd= mem= cache= wd
Press F3 to return to the main RecoverEDGE menu.
All future media images created will have the extra flag automatically added.