I just got the ACS freewheel spanner tool $19.99 through dans comp. I tried it out last night on a wheel which has had the same 18t claw on it for more than a year (I have several bikes and this one doesn't get the most ridding, if I only had one bike the claw FW might only last 6 months. ) The interface of the tool fits onto the FW very nicely. There is a hole for the axle to go through and you can put the bolt on the other end to stabalize it, don't put it on too tight cause as it loosens it will jam against the bolt(I know)
So I put the end on the FW put the bolt on some to stabalize it and tried to push it down. Well it didn't work right away, this FW was on there a long time. So I hit it with a big crecent wrench, still not yet, but you probably shouldn't hit it with a crecent wrench, then I found my big rubber mallet, hit it two or three times, and it worked, not quite as advertised, but it worked. I suppose you could also have put a pipe over the tool as a cheater bar and worked it that way as well. I'm sure that if you make sure to grease your FW when you install it or use antisieze, or change your FW more often it would be even eiser.
I had tried this FW with the park tool and a bench vise but had given up, but to be fair the table that the vise is bolted on isn't as sturdy as it should be. I think this is probably the best tool for removing FW, cause the interface works good and is permenently attached to the lever, so you don't need a wrench or a big crescent wrench on the tool for it to work.
If your still using bmx FW's I suggest you buy this tool so you don't have to constantly pester your LBS for gear changes, though some will change it out for free if you ask nicely and buy the new FW at their shop.