The above solution by all means works if you can find your friend in match making.
I found this rather difficult to do so what i did was play legit -
IF ABOUT TO LOSE - PRESS YOUR XBOX BUTTON - TURN CONSOLE OFF -
When loading the console back up - your record in achievements should still be tallied from your last amount of wins -
I had 4 legit wins in a row without turning my console off - on my fifth game my opponent was beating me so before he could kill my last worm, i turned my console off - when turning back on i still had 4 wins in a row - i then lost again - turned my console off - and came back still with 4 wins
- i won one more game and the achievement steamroller unlocked -
HOPE THIS WORKS FOR YOU AS IT WORKED FOR ME