Do you mean actual wax or sealant? I don't think either will be easy to apply and is probably not recommended by the manufacturers in below zero temps.
I just washed my car today at a wash bay with the pressure washer. I take my own buckets and soap etc. and just use the bay for their water and a dry place to work. I suggest you just do that on a regular basis until it warms up to at least 10C. Spray under the Jeep too to rinse salt residue off. My $.02.
