a) get ei.cfg remover
If you don't wanna mess with image, nor rebuild it. This little thing will do everything.
b) You don't need whole WAIK (~ 2 GB LOL!). You need only imagex (4 MB), get it here:
It's in tools\amd64
folder. Which one you need is up to your running os. You can delete the rest.
c) use imagex export commands like newtekie1 says and if you wanna compress them a bit:
imagex /compress maximum /export "c:\Win 7 x64\sources\install.wim" 1 "c:\Win 7 x86\sources\install.wim" "Windows Home Basic"
d) You can make your dvd bootable with oscdimg
oscdimg.exe –l<Disc_Label> -t<MM/DD/YYYY:HH:MM> -m -u2 –b<path_of_bootable_img_file> <path_of_installation_source> <path_with_filename_is_to_be_created>
e) when iso is done you can burn it with windows built in burner