How to clean the dust under MacBook's keyboard?

I have a lot of issues with the new MacBook Pro's keyboard. The computer is nearly 6 month-old, so there are a lot of dust under the keyboard and sometimes, some keys don't work or if I press it, it types 2 of the letter or number. If I turn one the backlight, I can see a lot of dust, so I would like to remove them.

How can I clean it without loosing the warranty or damaging the keys?