After the water pushback was nerfed, cannonballing became a lot less useful and a lot less fun.
Never fear, however, as I have found a method that is even more inefficient than qrweqq (or qrseqq) then qrqrqrde originally seemed.
The method is as follows:
Spin round so your back faces your enemy,you need to make a small counter-clockwise aim adjustment for some models.
Standard cast a rock wall, ed.
Hold the block key, and cast wdqq or wdqqq (or sdqq) with standard cast, but hold your right click down.
Then type your ice shield, qrqrqrde.
Release the block key, which will cause your wdqq to begin charging. Whenever you like (it can be fast) let go of right click, and quickly hit self cast to get your ice shield up.
I find the speed of the sdqq movement to be too fast to cast qrqrqrde in time, hence the convoluted block trick.
Don't know if that makes any sense, but try it for teh lulz!