You cannot run the Beta1 in the Editor without the .cry file for the maps! .cry files will not be released to the public.
Actually.... Yes and No....
You cant get the .cry files because they aren't being released and if they were that would tac on another 3-5 gigs to build so... yea!
But if you do want to run the editor with the MWLL Build you can navigate to your crysis folder, find the Editor.exe right click, send to desktop, once its on the desktop right click the Icon and hit properties. Go to the target Line and after the text type " - mod mwll" this will now launch the editor using the mwll mod. So it should look like this "....\Editor.exe" - mod mwll"
Helpful INFO
You can place mechs down by navigating to the Entities folder in the Rollup bar, placing the entity where you like, then select the entity again, on the side bar look for Modification, you can type either "prime" "a" "b" or "c" (for the different loadouts) then hit enter. Once you've done that you navigate to "Tools" on top window menu, and hit "Reload Scripts" VIOLA! You have a mech! Enjoy!