Since the numbers used in the kits in Tactic screen are pictures, and they are not made from the skin's fonts, dforlan (FM Greece) made three different styles to replace them.
This first one features the numbers used by the Premier League teams.
The files can be opened with Winrar, and then extract the "pictures" folder in the 'My Documents\Football Manager 2010\graphics' folder or where your user data folder is (the folder that your save games are).
Then, in the game preferences, you should un-tick the "Use Skin Cache", and either restart the application, or tick "Reload Skin on Confirm", for the numbers to be shown for the first time.
You may only have only one set of numbers styling installed.
Thanks to dforlan @ FM Greece.