XML : XSLT rendering a sorted node sequence as M x N table

There is a 5 year old question (linked below) regarding rendering a node sequence as an M x N table in XSLT. The answer works just fine and I have used it in several projects.

Rendering a node sequence as M x N table

I now have a situation where I need to have a sorted output. New items will get added to the end of the sequence, and I can't simply regenerate the XML.

It seems to me that using this code as a starting point, one would have to have the list sorted prior to calling any templates. I've not been able to come up with a solution, and hoping one of the guru's here can help.

Thanks in advance