This has been discussed before and it works great.  Heres a link I found
when I did my heads about a year ago.  I'm not sure about the screwdriver
idea, but the open end wrench works greak:

http://gerry.vanagon.com/cgi-bin/wa.exe?A2=ind9907A&L=vanagon&P=R10515

b

On Fri, 24 May 2002, Kenneth Wilford wrote:

> I was removing a pair of heads from a syncro Vanagon yesterday in
> preparation of installing new heads and gaskets.  The cylinders were stuck
> on tight and a thought occured to me that I have never heard anyone discuss
> before on the list.  You know the little metal ears on the cylinder barrels.
> I normally would stick something between these and the head and bang and pry
> until the heads came off.  Never hurt anything this way, however it took a
> while and alot of prying to get the heads off.  Yesterday I got another
> idea.  Instead of trying to break the cylinders loose by prying them away
> from the heads.  Here was my idea: why not use a screw driver, put it up
> against one of these tabs and hit the screwdriver head with a hammer.  Do
> this on an angle so that what you are actually trying to do is to turn the
> cylinder just a little.  I did this and within a hit or two the cylinder
> barrel turned just a few degrees.  Then I went to the tab on the opposite
> side of the barrel and tapped a few times until the barrel turned back.
> Then I did this on the other cylinder.  Now that these were broken loose it
> was very easy to put a screwdriver between the two tabs in the center of the
> head and give it a very minor pry and the head came right off!  I tried it
> on the other side and it worked great!  Anyone see any problems in doing it
> this way?  Since you are hitting the tabs are you not damaging the cylinders
> and you really don't have to hit them very hard to get the cylinders to
> turn.  You only have to pull the cylinders out 1/2" so that you can get the
> end of your flat head screwdriver in there to do this proceedure.  Normally
> taking off heads that are really stuck on could take 30 mins and alot of
> hitting.  This was like 5 mins for both sides.  I am happy.  I hope this
> could help other folks.
>
> Thanks,
> Ken Wilford
> John 3:16
> http://www.vanagain.com
> Phone: (856)-327-4936
> Fax: (856)-327-2242
>