Using LCD Display as Viewfinder on Pentax *ist DL

I recently purchased the Pentax *ist DL. This is my first SLR, digital or otherwise. I want to know if its possible at all to use the LCD as a viewfinder, the way most regular digital cameras can. If it is possible, I can't figure out how. Any help would be appreciated. Thanks in advance.

It is not possible.
Very few digital SLRs offer this, primarily because the design of a conventional DSLR prevents this from happening.

Autofocus and metering systems are generally distributed between the viewfinder and the area beneath the mirror where a sub-mirror (behind a partially transmissive part of the primary mirror) reflects light down. Then you have the shutter itself in front of the CCD.

using live preview would require this all be gone, and the sensor must supply a video feed to the LCD. This is also a big battery hog.

Olympus and Panasonic if memory serves each have a single camera with this, in the OLY's case the easiest way to use it involves a second sensor in the viewfinder porro system.