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.