Have a riot shield class, get a partner and go to the tree beside the bomb to plant in Search & Destroy team spawn.

If you turn to your left as you spawn, your partner stands on the corner of wall the behind the tree, and you have to stand facing your partner with your riot shield on the wall also.

The combination is to run towards your partner with your riot shield and press RS then RB quickly, then you will go shooting up in the air (this may take a few tries).

It will be easier trying it in a private match first and make sure you and your partner are in different teams.