What about trying to resize the map image manually and using a lower-res version, but then zoom in to 200%?
Often, these map files come in a way too large resolution. Try to reduce it to 50% and 33% of the original size and look if there is indeed a loss of real information or if you can live with the smaller version.
(I've successfully applied this method on map images here in the past)

debernardis, it works! With the Google Map Image Cutter (GMIC) at level 6 a html file and 1264 tiles in jpeg format are generated.

lovepixel.gif (10000 x 10008, 14.8 MB) split to tiles is now 18,6 MB.

I copied the html file and the tiles to my N810 - in the browser, zooming and panning works!

Then I hacked the html file to load a local copy of the google javascript api.
Unfortunately the browser still insists on a internet connection at first. I have to find out what's causing this.

WOW. are we supposed to find waldo or something?

i dunno, it was just the picture I was sent by the original poster to test in liqbase.
I thought it would be a reasonable image to check alternative methods.