For some reason, control/click isn’t doing it for me in Safari or Firefox - Devon just isn’t coming up as an option.
Here is something slick, which BareBones has implemented in their new update to Yojimbo: there is a “how do I” in Help, and when you click “capture web pages” it leads you to web pages where you can drag and drop bookmarks to the bookmark bar of Mac browsers: “Archive in Yojimbo” and “Bookmark in Yojimbo.” Really works!
If you have installed the scripts (there’s the option the first time you launch DT), then i the scripts menu is “Add Web Archive to DEVONthink.” That’s not workable enough?