[Libguestfs] Can I update a specific package with virt-customize/virt-sysprep

I'm using an image (Fedora cloud) which apparently doesn't have iSCSI kernel module available as-is. I therefore need to update kernel-core in order to get it. Is there a way I can do it via virt-sysprep / virt-customize? I would like on the first boot already to use iSCSI (I'm using a script there to already login to a target, etc.), so first boot (+ it'll require an additional boot anyway) is too late for this. Is there a way to do it, as it seem 'update' updates everything (and thus bloats my image a bit). TIA, Y.