You can't. Maximum size is around 4000 x 4000. Even at that size you will quickly bring PR to it's knees. You need to devise another way to achieve your purpose.
I know it doesn't exactly help with your specific question - but thats a task that would be much better suited to After Effects.
I've had great success working with large images (though I don't honestly remember how large I've gotten), and the animation & keyframing are much more intuitive in AE and PP.
I agree completely about using AE for this. The motion-tracking controls will be better also.
I would also NOT use JPEG if one wants ultimate quality. Stay with TIFF, or PSD for the source material and do not use JPEG, even at max settings.
PS some years ago, Curt Wrigley did a tutorial on creating a "photo wall," in PrPro 1.5, IIRC. You might want to search his SITE for that tutorial.
I though AE also has a 4096 x 4096 photo res limitation.
30,000 x30,000 except ofr Pict and Bmp n(16,000 x 30,000).. It all hangs on how much RAM you got.