In your library folder navigate to PCB > Surface Mount and load 'QFP_Thin_Sq_50P_Side_N
I think that's a thin version of the same size package so the only difference is the height of the component. It's the one I have used anyway and the manufacturer was able to fit it without any problems.
For 8322 device I've used TSQFP50P900X900-48N
Alternatively, you can use the LP footprint viewer from
http://www.pcblibraries.com/ to get the dimensions for the footprint (you may have to check freescales datasheet to get the JEDEC standard # and look that up in the viewer). Then you can simply stick all the dimensions into Altiums IPC Footprint Wizard and it will automatically generate it for you with all the correct layers, dimensions, keepouts etc!
You may need to add a fiducial mark or two to the footprint to aid the pick-place alignment. One on one corner at least, and if you have the space, another in the corner diagonally opposite. (obviously place these outside the component area)
Hope that helps! I find the LP viewer extremely useful in finding unusually named footprints as you can look things up by their common name or by the standard to which they conform.
Steve
