Not sure you can do 10kg in 4 weeks healthily but here are my tips:

workout 6 days per week - use a heart monitor and burn at least 500cals each sesion (and ideally double up one day).
do 3 cardio workouts, 2 resistance (like pump), 1 yoga/pilates a week
If you want some help maybe buy some DVDs (Michelle Bridges ones are great - super shredder)

Eat no more than 1200 cals per day - 3 meals of around 300 cal each and 2 snacks 150 cal each

hmmmm - sounds easy doesnt it!!! LOL!
om this regime 1/2 - 1kg a week is doable