You should be able to purchase a non-owners insurance policy
and have an SR22 attached to that policy to meet the state requirement. It would be impossible to install an interlock device if you don't have a vehicle so I would recommend contacting your probation officer or attorney to discuss your options. It's very possible that you were required to have one installed since you owned a vehicle at the time of the violation. You may not be required to have one if you no longer have a vehicle registered to your name.