The camshaft plug?

I just replaced the valve cover gaskets and I still have an oil seep. I also replaced the RTV on the little half moon aluminum piece but have a seep from behind the cam on each head. The part is #14 in this illustration.

I have to replace them and want to do it without removing the heads. Anyone done it and have any advise??

Thanks.
http://www.trademotion.com/partlocator/i...p;Sectionids=10,4117&groupid=10007&subgroupid=61318&componentid=0&make=34&model=T100&year=1996&graphicID=F809084&callout=14&catalogid=1&displayCatalogid=0