Just poping this link here for all curious. I have yet to try it myself, but the folks over at Ryandor.com claim to have figured out how to change the map size in the client.
Link: http://www.ryandor.com/forum/viewtopic.php?t=2775
How To: Custom Map Sizes
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Bmzx007
I don't claim it, I know it 
It has also been verified by others since then as fully working. The only thing I need to do, or someone else needs to do, is create an automatic patcher.
However, as stated there are a few limits to this, but it still gives us much more flexibility than before. Mainly with the Wrapping Points and Non-Map0 maps (You can now have 4 full-sized maps).
Currently there is no software that can create a map larger than map0.mul. UOL (1 & 1.1) has set limits, and Dragon (v2 Alpha) will do the map, but the static patcher will crash.
Punts Worldmaker suite currently can do it, but I beleive the transitions arent complete, my best bet would be his software for now if you want a bigger map or unusual size.
UOL2 is the other option, but it isnt out yet. And Dragon is no longer in development (Unless someone wanted to re-write the static patcher).
If you have any questions about it, feel free to PM/Email/Contact me about it, and I'll help you if I can.
It has also been verified by others since then as fully working. The only thing I need to do, or someone else needs to do, is create an automatic patcher.
However, as stated there are a few limits to this, but it still gives us much more flexibility than before. Mainly with the Wrapping Points and Non-Map0 maps (You can now have 4 full-sized maps).
Currently there is no software that can create a map larger than map0.mul. UOL (1 & 1.1) has set limits, and Dragon (v2 Alpha) will do the map, but the static patcher will crash.
Punts Worldmaker suite currently can do it, but I beleive the transitions arent complete, my best bet would be his software for now if you want a bigger map or unusual size.
UOL2 is the other option, but it isnt out yet. And Dragon is no longer in development (Unless someone wanted to re-write the static patcher).
If you have any questions about it, feel free to PM/Email/Contact me about it, and I'll help you if I can.