As previously mentioned, your printer must be able to handle the "oversize"
stock.
If it does, you may find you have to rotate your print image by 180 deg. as
usually the printer will take the divider "backwards", i.e. the non-tabbed
side first.
To get you started, go to the Avery or MS websites as they have pre-setup
templates for the various types of dividers, just download the one you want,
i.e. the stock size, say Oversize A4, and what design of tabs, say 1-5 tabs,
and off you go.
Hope this helps
DeanH