Heck, I think if you just do a forum search here with X1 in the title, you will find a thread with some posts by a Joseph in AL that gives an "agreed" set of custom settings for the X1. I know cause he posted it for me when I had mine. I even printed it out and kept it. But I have since upgraded to the 4805.
You can't really do a one size fits all calibration on any display. There might be some settings that will improve the overall picture, but to do a good calibration you have to take things like ambient room light, screen type/color and distance from lens to screen (and many other things) into consideration. Things that are different in every setup.
Pick up a copy of Avia or Video Essentials (or even a DVD movie with the THX Optimizer on it) and do a true calibration on it.
A good start is to use the "THX Optimode" on a disc that comes with it, many recent DVDs. I used Raiders of the Lost Arc on my X1 and the results were great. I've gone back and changed it some more with "Digital Video Essentials".
Personally I feel the best results are obtained by flashing to the 4800 firmware and leaving it on the default film setting or tweaking it slightly to meet your needs.
Some people claim that the same results can be had with calibration, while others have said the 4800 has an altered gamma curve and no amount of tweaking with the x1 can obtain quite the same level of picture quality.
Either way I feel its probably easier to flash to the 4800. Even if the default settings are not perfect for you, they are probably a better starting off point then the x1 default settings.
And you can always flash back to the x1 firmware if necessary. Check the x1 faq or the avsforum for details if you want to try it out.
If you flash the 4800 BIOS into the X1 you'll lose the "Effect" key. I use that for aspect ratio control so I'm not willing to do it. I just calibrated my X1 with DVE a couple days ago and the picture is fantastic, much better than the Optimode thing, the color and tint are -way- out of whack by default.