I've been wondering how one would tell time in Dovahzul. Would it be like counting normally like "It is sed nenahrkmen"? With the o'clock it might be kind of tricky. I don't know, thoughts?

This is a good question.  One possible way might be "thirty-eight past five", or "seven past midday".  Translated, "eln ahrk men sed on hen", and "zos on hefsul".

In French it is something like "it is 9 hour". 

So, "Los nen omaar"

Half past nine hour, "Los hef on nen omaar".

Half of nine hour (aka 8:30), "Los hef nen omaar".

Or just leave off the "hour" at the end, being implied.

I think the 24 hour clock would work better IMO.

What about measuring it in hours, saying "first hour", meaning 1:00 AM to 1:59 Am, to the "twenty-fourth hour", meaning "11:00 PM to midnight"? Or in half-hours?