The simple answer is No, right now theres no way. Maybe in the future they will add it to the list but as the S and X are not on the list I doubt the 3 will make it. And if it does who is going to supply the parts to make it compatible and at what time frame, you only have 45 days and its not as if Tesla move fast on doing this.
Read this thread and you will see only a few reasons why it's not just hard but impossible impossible.
Road Trip to California for Delivery??
And trust me I have imported cars before, from Porsche's to Mercedes and my Tesla.
Tesla is in a different league for importing because it's not like you can fit an aftermarket immobilizer, you need to integrate it to the rest of the system. And you should certainly pre order all the labels than need to be changed. And its not like you can turn the headlights on and leave it there, you have to either ask Tesla to reprogram the can bus, or do it yourself. And yes, RIV want proof of all these things before they sign off on it, but thats a moot point because unless your cars on the list then its either allowable as a temporary vehicle or its staying on the US side.
Vancouver is slightly different in as much as $300 will give you a temporary permit with full coverage for 14 days and will cover you in the US, but you have to pay tax in Vancouver, Tax in Ontario and then claim the Vancouver portion of the tax back. Thought about that as my car came form Anacortes.
Its not the answer you want, but thats the honest truth, as soon as the model 3 comes on the list make sure you can have the car reprogrammed before you get to excited. The ability to reprogram a US car and the immobilizer that runs on a different frequency using Canadian equipment may or may not be possible. those 45 days will tick by fast.