Ah! Tarrasque!

[Sejs]

I'm BRILLIANT!

Darkness helped a bit too with this idea.

Cast Fox's Cunning on the Tarrasque. Or, if you don't think you can get through its SR, put a Headband of Intellect on it. Or just keep trying.

You now have a sentient Tarrasque.

Now, cast Tongues on it. Which doesn't bother with SR, by the way, so just cast as you wish.

Now, it is smart enough and capable of understanding you.

Got someone with a good diplomacy score? Take some time, talk it into being helpful to you. Maybe have it eat the guy who likes to screw around with creatures beyond the ken of mortal man.

A smarter Tarrasque just means he'll eat you on toast rather than eat you raw.

 

[Sejs]

Alternatively, sneak up on him at least 24 hours before he wakes up, and slip a Ring of Sustenance on his claw.

Then, when he's woken up, he's not hungry, so he has no reason to rampage eating everything out there.

168 hours - the ring takes a full week to attune.

On the up side, he's not hungry any more.

On the down side... he needs a lot less sleep, and just because he doesn't need food doesn't necessarily mean that he won't still eat just for the heck of it. Wearing a Ring of Sustenance doesn't mean you -can't- eat, after all.