I have most of the process for the KF2 outlined over on this guide (minus the software part for now), but if you don't want to read that or the other post, here's a short rundown: You solder to a few points on the motherboard, allowing you to bypass the KF's processor and directly access the information on the eMMC. This allows you to reflash whatever it was that you flashed in the first place to kill said KF.
Once I have word from v0id7 that this does indeed work on the 8.9" (which I can't foresee it not working), I'll probably set up a guide specifically for the 8.9", as well.
I'm also in the process of prototyping something that would allow access without soldering. Hopefully I'll have the prototype done in the next few days here.
Let me know if you have any questions/comments/concerns.
...and now that I've blathered on for a while, here's the pinout: