In my OpenLdap we have ACL policies is there any script available to
convert OpenLDAP acl policies to 389-ds policies.?
There is no script that I am aware of for such things. You will need to
recreate them manually.
As for your IRC question, you can not have a single ACI with allow and
deny rules. You need two separate ACI's to do that. If you give us
some specific examples we can help with the syntax, etc.