Ordered lists can start at any value. This is somewhat related to the LI.value property, which allows the list items to begin sequencing from any value you care to define. The value you specify here must be a positive integer.
This exhibits some bugs in Netscape 6.0. Setting a start value seems to be applied inconsistently to the items in the list. They are renumbered but not correctly. For now, the best workaround is to construct the list and use the innerHTML trick to store it into the page. This will likely get fixed as soon as people really get to grips with Netscape 6.0 and it does work fine in MSIE.