Yeah, kernel with modules doesn't take much space, less than 10 mb. If you can wait a little bit longer, Pali is working on integrating wifi pathes to main power kernel (he already released power kernel 47 with many improvements), so in near future installing multiboot and power kernel with wifi pathes will be as simple as: install multiboot, install (or reinstall) power kernel, install additional packages (also via app manager or apt-get in command line) to have entry in multiboot and wifi bleeding edge driver (Pali suggested that driver will be available as external package). See power kernel 47 announcement thread for more information