Does Pathfinder have anything like a dreamscape? Essentially it's "the plane of dreams" or whatever, but it acts like a virtual world. Effectively it's a fantasy internet that you log into and have an avatar. There was a show that was a Battlestar Galacta Prequel (the exact name escapes me) where they had such an internet technology. It would work like that.
If not can anyone suggest rules/spells/etc for using such a thing?
Guess not.
Psionics, Psionics, Psionics.
That is all.
Closest thing I can think of at the moment would be astral projection spell as it creates a temporary body on whatever plane you are traveling to.
You could also introduce an artificial psychic plane that can be accessed through some sort of ritual drug that was build by Azlanti, Thassilon, Serpentfolk or maybe Aboleths. Maybe Serpentfolk build it and Azlanti waged war on them to gain access to it, or maybe Aboleth built it, Azlanti utilized and Serpentfolk intruded upon forcing Aboleth to send Azlanti against them?
Like tel'aran'rhiod in WoT?
I recall from When the Sky Falls they explained the Rune Pool and the runes floating within are memories of the dead race who fled from their destroyed world, maybe try something like that? The idea Drejk put out would be interesting, combined with the idea of a pool of memories it could be the entrance to awaken azlanti blood in sorcerers or unlocking certain 'magics' unknown in modern Golarion. Aboleth might even have a artificial psychic network connecting their servant races to their mind, possibly manifesting as a massive pool with a model of their lair with small floating dots representing their network.
Another idea: dreamscape is created by emanations of dreaming humanoid minds - after reaching certain critical mass of dream emanations they mingle and start to form independent psychic plane. Aboleths (or maybe some other elder creature - vault builders?) deliberately manipulated evolution of humanoids on Golarion to grow their brains according to specifications that would allow them to generate dreamscape. The same would apply to many other humanoid species on Golarion and beyond, except Elves that weren't manipulated in this way making their minds working differently when it comes to sleep and dreams (and this being the source of their sleep and dream effects immunity).