Login to M5 and click on "groups"
Edit or create an "item group" you wish to setup the hourly loan period for by clicking on the pencil icon (as shown on the right).
Select "circulation periods", set the loan period and click "ok". Please note: only full hours work, not hours and minutes.
To assign the item to the group with the hourly loan period, search for the item and edit the holding. Look for the 991a field or "group", click on the drop down menu, select the item group you have set the hourly loan and click save.