Infinite SEO "switch to per-blog mode"

How does one "switch to per-blog mode"?

I would like to offer Pro Sites access to Infinite SEO as a premium plugin - can I do that? It doesn't appear in the list of available plugins in the Pro Sites premium plugin setup tag, even when it is network disabled.

I have set "show to site admin" on for XML sitemaps, and for Title etc optimisation. and although the Infinite SEO stuff appears when editing posts on my main site, I can't access the setup menu.

It also appears in the post CRUD page for other sites in the network.