I usually use the original hood that came with my 24ASPH, I just put a 55mm wide angle hood (from Heavy2Stars on eBay) on it for the purpose of this shot (I've been using the hood on my Tri-Elmar).
m8-24asph-heavyst.jpg
The hood takes a 58mm snap-on cap from the same selle as a hood cap. Works great.
Here is an attempt to illustrate what the Heavy2stars hood (top) and the original Leica hood (bottom) blocks through the finder. These are not 100% accurate, but give you an idea. The hoods seem less dominant in the VF than the impression they make in these shots. (I got them using my cell phone's camera.)
24asph-heavyst.jpg
24asph-leica.jpg
Cheers,
- Carl