One would need to install Web+ from the official repo, then switch to the "bottled" one to install/update everything else.
Ideally, each repo would have a different "URL" identifier in their metadata, so it's possible to use them side by side. But that is currently not the case, so adding one will remove the other.
As for the official switch, I'd be tempted to say "go ahead", but we need to figure out the remaining problems such as why WebKit is failing to build there (and if possible, solving that without bumping revisions a dozen times).
Not much available time from me in the coming weeks, as I'll be preparing for GSoC mentor summit then a week vacation in the US, and then when I'm back, finalizing the coding sprint organization (with some other non-Haiku events interleaved for extra fun). So someone else will have to care for that!