Is it possible to install Mac os x in virtual machine on a macbook pro

While Apple stated that Leopard was required to install Snow Leopard, there was no technical limitation put in place.

From the day it came out Snow Leopard could be installed over top of Tiger or as a clean install. I don't believe Apple has ever released an 'upgrade' OS. The full installs have always been available, at least since OS X.

The MBP model you have shipped with version 10.6.3 build 10D2094 -- this is a special build of 10.6.3 with support for that model (and probably some others released at the same time) added. Anything older, including the standard build of 10.6.3, won't have drivers/config info/etc for that model, and hence cannot boot it. It sounds like your retail disk has an older version, so it won't work on that Mac.

If you have the installer DVD that came with the computer, you can use that. Otherwise, if you have another (older) Mac with FireWire, there's a trick you can use: start your computer with the T key held down, and it'll go into target disk mode, which essentially means it turns its brain off and acts as an external FireWire hard disk. Connect it (via FireWire) to an older Mac, start the older Mac from your retail 10.6 DVD, and have it install onto the "external disk" -- the MBP. Then, restart the old Mac from the "external disk" (the MBP should still be in target mode at this point), and update to 10.6.8. Now that the OS on the MBP's disk is new enough to support it, shut everything down (older Mac, then the MBP) and restart everything from its regular disk.