The tutorial at Shiny Things seems sort of reasonable, although a bit hacky for me to risk right before I leave.
The best way to handle this I could imagine is: connect my iphone to a different itunes install and have the option to "recreate" my library there, copying over all my media, settings, etc, so I can at least start from the same place.
It's not a big deal that I can't add new media while I'm gone. The biggest issue would be if a new OS version is released, I can't upgrade until I get home. But, if they finally release multitasking or PNS, what's a few more days?
I'm still not convinced on the whole iTunes take-control-of-your-library model. I regularly use at least 4 different computers, so being tied to just one for my iPhone is annoying. I know it's archaic, but I was fine with manually copying music files to other media players, although I guess I am starting to like some of the features in iTunes.