Tough call- Forget the waterborne- won't help you at all. Just an idea- a clear oil with paint as the pigment, figure out the proportions.
Another possibility is to use Universal clear shellac with a mix of pigmented bin as the colorant. that will stop the tannin well, then top coat with oil finish of choice. Stinks like hell and dries fast, but will hold 'er back. You could also use the shellac after the stain, but I don't think it makes a good top coat.
Brushing or spraying? I would assume brushing- I've done some log home int and there are so many nooks and crannies it almost has to be at least backbrushed.
Good luck with that one!
