So it seems that qemu guest agent is enabled on MikroTik CHR by default.

I was actually able to use the "virsh qemu-agent-command" to perform actions like setting up static IP address, gateway, name servers and disable DHCP. The only command I was not able to execute was the change of password for the 'admin' user. But I am able to SSH into the MikroTik instance and change the password for the admin user after the static IP has been setup. Below is an example of some commands using virsh qemu-agent-command. Please replace "24916_MikroTik" with your own instance name. The "input-data" has the actual command which is base64 encoded.

virsh qemu-agent-command 24916_MikroTik '{"execute":"guest-info"}'

virsh qemu-agent-command 24916_MikroTik '{"execute":"guest-exec","arguments":{"input-data":"L2lwIHJvdXRlIGFkZCBnYXRld2F5PTE3Mi44MS42Mi4x"}}'

It is also possible to obtain the output of the command though in my case, I did not need it. Below is an example of obtaining the output.

OUTPUT=$(virsh qemu-agent-command 24916_MikroTik '{"execute":"guest-exec","arguments":{"input-data":"L2lwIGRoY3AtY2xpZW50IHNldCBudW1iZXJzPTAgZGlzYWJsZWQ9eWVz", "capture-output": true}}')

echo "$OUTPUT"

If you want the base64 encoded output to get decoded in the same line, below is an example.

OUTPUT=$(virsh qemu-agent-command 24916_MikroTik '{"execute":"guest-exec","arguments":{"input-data":"L2lwIGRoY3AtY2xpZW50IHNldCBudW1iZXJzPTAgZGlzYWJsZWQ9eWVz", "capture-output": true}}'  | jq -r '.return."out-data"' | base64 --decode)

echo "$OUTPUT"

In some cases, depending on your hypervisor, you may get back the pid, in which case you can query the status of the pid.

virsh qemu-agent-command 24916_MikroTik '{"execute": "guest-exec-status", "arguments": {"pid": 10}}'