…not quite sure what you are saying here, but virtio network (and disk) drivers should work out-of-the-box, hence no need to install them in CHR image separately.
There is no need to enable these things, they are available or they aren’t.
E.g. in VMware ESXi the “vmware tools” is installed in CHR. At least now it is, some time ago that wasn’t the case and it showed the same message.
Maybe it depends on what image file you use for the install, use the one that seems most appropriate for the hypervisor. (I use OVA for ESXi)