How to create Previous/Next subcategory links in any given Category?

For example under Europe Category if the visitor is in "France" subcategory page the previous link should go to Finland and next link to GERMANY.

The sequence should be alphabetical and it should loop.(see examples 3 and 4)



1.
<FINLAND GERMANY>
FRANCE


2.
<FRANCE GREECE>
GERMANY


3.
<VATICAN ANDORRA>
ALBANIA


4.
<UKRAINE ALBANIA>
VATICAN


Thanks.