Started poking around. Here's one chunk of one of the pages at one of the higher resolutions: http://www.bl.uk/manuscripts/Proxy.ashx?view=arundel_ms_263_...

Looks like the format is:

  http://www.bl.uk/manuscripts/Proxy.ashx?view=arundel_ms_263_<page_number>_files/<resolution_level>/<column>_<row>.jpg

Pages work in this fashion: f001r, f001v, f002r, f002v, f003r, f003v, ... and ends at f283v.

At resolution 14, columns range from 0 to 33 and rows range from 0 to 24.

Edit: I hacked together a python script to download all images at resolution 14 https://gist.github.com/L1fescape/4761013

Now to figure out how to combine them all...