Success! I created a function that should work to install refind.
- no support for lvm, luks or btrfs subvolumes (to be added)
- no support for intel microcode (not feasible to add with this method and potential for multiple kernels)
It also detects if the target drive is removable and installs drivers accordingly.
This is using refinds automatic kernel detection.
EDIT: added support for btrfs subvolumes, lvm and encryption. Caveat emptor, no idea if it works.