It's not a particularly simple problem to solve, for a number of reasons. One is that the whole installer image needs to fit in memory, so you add a lot to resource requirements if you need to compile from source (ie, the way the kernel mods are currently installed via DKMS). The only way to avoid that would be to precompile binaries for all the installers you want to support, then serve them via HTTP or something for the installer to download. The problem with that is, what happens when you don't have a net connection at install time? It's also pretty inefficient, since you need to serve the bins up every time an install occurs, rather than just once when the installer is downloaded.
Originally Posted by mo0n_sniper
An alternative to serving via HTTP might be to offer some sort of ability to use supplementary media, like a USB stick, to load the binaries but you've still got to compile those binaries to match every installer version you want to support (and add those media hooks to all the relevant installers). That's a fairly significant (and ongoing) task, particularly when installation media may get point releases that require new bins.
If you have the memory, using a livecd should already give you a moderately simple path to doing an initial install onto ZFS, since you should be able to boot to the live environment, install the packages as normal, prepare the disks as ZFS and perform the install onto them, then chroot into the install and perform any final configuration (here's a link for HOWTO install Ubuntu on ZFS root, haven't read it in a while, but from memory that was the gist of it).