Tablet [Q] How to enter secret codes?

Hi,

Many poeples give secret codes for Galaxy Tab but no one explain how enter them in a tablet (With no dial).

Please can me tell me how to access these secret menus.
I would like to display my product code.

On this post http://forum.xda-developers.com/show....php?t=1479322 , "SGS Secret Codes" is mentioned. However, it is not available anymore on the market.

What is the best method to do that ?

Thanks