Zero chance for that, unfortunately.

I'd try to checkin online with Air China. If it doesn't work, head for connections/recheck of baggage for domestic flights at the lefthand side at the baggage carousel area. Don't completely go landside. They can check you in there.

Others might say that it would be a better idea to get the boarding pass from the "transfer counter" while still in the international area at T3E, but from what I've read (never had to use them myself) they're not always staffed or usually take a while to understand what you need. If you're arriving on time, I'd probably head towards the domestic area (ie, through immigration and the train to main terminal) and sort it out there. But as said, others might disagree.

If you're late but still within the checkin windows, getting to the transfer counter in T3E might be the only option, though. CA T3 domestic unfortunately is 45min cut off time. That was improved at Daxing, by the way