Yes, with Multiboot you can have it run a script to change the uboot load script instead, but I feel it's just more round-about that it has to be. Though I'd be happy for that being available as a package. I'd work on a u-boot only solution, but I can understand that most would gravitate towards a UI-only approach, and being able to type a command is a lot less convenient than up/down arrow key-ing, even if the command to be typed is written on the uboot screen (like "run noloboot" is now).