You just need to find out the ACL by running an ls -V on the directory (in this example, I'm running it on the root directory from /:
drwx------ 4 root root 10 Feb 25 2011 root
owner@:rwxp--aARWcCos:-------:allow
group@:------a-R-c--s:-------:allow
everyone@:------a-R-c--s:-------:allow
You can then run a chmod -R A=<<INSERT ACL HERE>> * on the directory, where <<INSERT ACL HERE>> is replaced with the acl as listed in the ls command.
In this case, I'd cd root and then issue chmod -R A=owner@:rwxp--aARWcCos:-------:allow\ group@:------a-R-c--s:-------:allow\ everyone@:------a-R-c--s:-------:allow *
This usually works for me.