Go into any motorfactor / pound shop or wherever and buy the cheapest compressor you can find.
Take it home and remove (carefully or with a lump hammer) all the bulky outer casing.
You'll be left with the same basic compressor that goes into most tyre inflating systems, only now it occupies far less space.
Try it on the auxiliary socket, it may run, it may not. It may run and then stop when put under load, it may not. If it doesn't stop, job done. If it dies, go direct to the battery via crocodile clips and a suitably fused lead, or fit a second auxiliary socket separate to the Canbus, with or without a relay, as you see fit. There is a good sticky on how to do this. It's fun and you'll have a real sense of achievement when completed. You may even save money to spend on fuel and clock up the miles, making all the effort very worthwhile... Though increasing your (slim) chance of a puncture; so it's a double edged sword.
One tip, the naked compressor will get VERY hot when pumping air into your awesome steed's tyres. This is not unusual nor alarming (unless you touch it) it's just physics.