Front suspension seized - what can I do
You didn't say where you live (what country?), so you may not have this particular option for a store, but you could use a 3/8" drive extension: 

http://www.lowes.com/pd_337346-22328-85817_1z0wcg7__?productId=3380286&amp;pl=1

With a 3/8" drive hex driver: 

http://www.lowes.com/pd_338623-22328-85226_0__?productId=3387790 

(You might also be able to find a T-handle hex driver that is long enough, although a quick google search didn't turn one up for me.)

This is of course assuming the base of the hex driver will fit into your fork tube, which it may not, you will have to check.
Also, before trying to loosen anything you should spray the bolt / any seized parts with penetrating oil (like WD-40 or PB Blaster) &amp; let it sit for a while. That alone might end up being enough to free the stuck parts.

If you do get it apart, you should really consider doing a proper overhaul on it &amp; determine if it is even fixable / worth fixing.