So you need dns servers or openvz servers? For dns servers, there is a guide available here that installs a primary and secondary dns server:
Ioenvz is something different, as you would normally not run any other services except of openvz on the host system. To install a openvz ispconfig server, see here:
So if you want to manage virtual servers with openvz, then you could e.g. install ispconfig as described in the openvz guide, then create openvz virtual machines in ispconfig and install the dns servers inside these virtual machines. The benefit is that you can backup the dns servers tlater easily with vzdump and make snapshots before you update software etc.