I'm not an 11C either, but we used to practice Call for Fire (Mortars and Artillery) all the time.
Yes, you could put a small (82mm) mortar, like this one
http://en.wikipedia.org/wiki/82-PM-37, in truck, weld the baseplate to the bed. Or tow it behind at truck http://en.wikipedia.org/wiki/2B9_Vasilek. Hell, we mounted 4.2 Inch Mortars in M113s. And we have Strykers that carry 120mm Mortars. Yes, it can be easily done.
I'm going to guess it was a Soviet era mortar, since that's what would have been fairly plentiful in Libya at that time.
If you have a GPS system to plot where the tube is, the firing tables for the rounds or someone that can so some advanced math (Trig), an observer, and a half-way trained crew; it's not that hard to put rounds on target. You are talking about hitting a decent sized building not dropping one in a pickle barrel.
How fast can they hang and fire?
http://www.youtube.com/watch?v=io3NHBKQSQ4Here's some Illinois Nasty Guardsman, taking their sweet time about it, and they four rounds off in under a minute.
http://www.youtube.com/watch?v=pBkcQ9b7Ot0So yes, AQ would have had to pre-plan at least a day in advance to plot the firing. Then you need a good crew. Our Mortar crews are good at "Hip-shoots", but that's because we practice all the time.