Depends on your particular model, your skill level, and the size of your cojones.
Instructions for various models have been posted here and there on the 'net. Try searching forums at
http://www.keohi.com/keohihdtv/index.htm or
http://www.avsforum.com/
If you crack the case, don't look at the lamp/lens assembly, though. A hair down there probably won't show up as a defined shadow. Think of it the way Mercury doesn't cast a shadow on the Earth - it's too close to the source.
If it's actually a shadow from a foreign object, that object is probably either on the mirror or on the inside of the screen.
(This will almost certainly void your warranty, so take that into consideration before soldiering on.)