I made a shortcut for btcQT and I've put the target like you said but when I press OK it says:
"Problem with Shortcut"
The name -datadir="D:\Bitcoin" specified in the Target box is not valid. Make sure the path and file name are correct.
And of course I don't know how to run it from command prompt
No, you need to add the argument to the END of the target line... like this:

NOTE: the first part of the target has simply scrolled off the side as the entry is so long... but it includes the FULL path to the bitcoin-qt.exe...
"C:\Program Files\Bitcoin\bitcoin-qt.exe" -datadir="D:\Bitcoin"