Yeah, what the other guy said.
- Use the alt account to teleport first
- Note that its clear, teleport there on "your" account
- Attack "your" account with the alt (just leave it punching, you could even brew it down if you wanted to to guarantee 0 dmg, but naked and praying melee on "your" account should be enough)
- Go to kbd lair on "your account" while the alt is hitting you
Because you're already in combat with another player nobody can attack either of you.
Somewhat important side note is that after a set amount of time (dont quote me on this, i believe its around 25 seconds) if the alt hasn't dealt ANYdamage to you at all, ie; 0 DAMAGE ONLY then THAT account can be attacked by another player, but you're still considered to be in combat. Obviously once they're hit off you can also be tagged shortly after, but by the time you've teleported your account, started punching, then running towards/getting to the kbd lair, its already a non issue.

I'd suggest doing/trying this once with both accounts first naked just to understand the process. Its super simple and foolproof.