The IR Cut pass Filter has to be there in order for you to take normal pictures. IR light really screws up normal shots. The reason some cameras are better at IR then others is due to the better ones having weaker IR filters, but those usually do not take as good of normal images.
The best way in a dSLR to shoot IR is to have your camera modified. But I don't know of anywhere that does Pentax cameras, just Canon and Nikon.
I like using my Sony DSC-F717 to shoot IR. Its NightShot mode actually removes the IR cut pass away from the sensor when turned on. So by using a Hoya RM72 or other IR filter you can do handheld IR shots. Bad thing, Sony firmware locks shutter speed to a max of 1/80th sec. So in good daylight an NDx8 is pretty much a must have!
But on the K10D it can still be done.
1. Set your custom white balance off a real green area
2. frame your shot up with the filter off
3. screw the filter on the lens
4. use the 2sec MLU mode
5. I typically shoot f/8
6. shutter speed will vary depending on amount of light available
7. ISO400 is a nice compromise for getting a faster shutter speed and just do some NR later
8. of course use a tripod
9. Using a red 25A filter on top of the IR filter will give you even darker skies and more distinct contrast between the clouds
If you want to play around but do not want to spend a fortune on an IR filter right away, find yourself an old 5.25" floppy disk. Take it apart and use the film inside and an old filter ring to make yourself an IR filter. Works nicely.
Hoya RM72 work nicely and allow you for those wildly colored IR shots, or just B&W as well, since it is only near IR and not a full IR filter like the RM90 or 87c filters.
Here are some of my IR shots:
Infrared Photo Gallery by JameyS at pbase.com
None with the K10D yet though.
When I sold all my Canon gear I did keep a 20D + 50mm f/1.8 MkII and am having the 20D converted over to full time IR by LifePixel
Yes, the Sigma SD14 is new this year, not to mention one darn fine camera!!! I dare to say, probably one of the best out there for Portrait, Landscapes, and Macro work! The FoveonX3 sensor just really blows the socks off of Bayer based sensors. The technology is amazing if you read up on/about it!! The output is equal to Full Frame really in details. It will go head to head with the 5D in image/print quality! But the colors are far more accurate on the SD14!!