Installer updating directory group privilege (ACL?)

Question

I'm deploying a project on another computer and would like to programmatically (C#) update a directory to include an existing group with write permissions. I've looked at various resources but would like to know if anybody can point me in the right direction on how to accomplish this. The condition property in the VS deployment seems limited for this task. I'm thinking that I would have the MS installer run my app during the installation. Thanks, Scott