Okay, I'm going to get openly Charismatic at you for a minute - I hope that neither you, nor any of the other RC folks on this thread find this offensive - appologies in advance if so!
Actually the whole labyrinth fol de rol, as currently used, is designed and intended to accomplish just what you described. If the instructions provided by the various 'pro-labyrinth' organizations are followed the labyrinth itself is laid out in such a manner that it forms a potential...well, call it a 'weak spot' through which spiritual entities (and we're talking demonic entities here) can exert some influence over those humans who move within it's boundaries. All of the 'centering prayer' and meditation nonsense that unsuspecting people are told to do in order to 'enhance their experience walking the labyrinth' has the specific intent of maximizing their vulnerability to external spiritual influences.
One interesting thing a Christian can do, if he has to be around one of these things (not something I recommend, but I understand that some heretical parishes have actually set these things up so you have to walk around them to get into the church building itself) is to -without entering the labyrinth - take a handful of consecrated salt, toss it toward the center of the labyrinth while quietly invoking the Trinity. Sometimes nothing obvious will appear to happen, but other times one can get some really revealing reactions from people who suddenly show up to see what's going on. In any case it isn't a waste of the consecrated salt, for all the obvious reasons.
As for the one historically obvious question: no I do NOT know why there are labyrinths on the floors of some older european cathedrals - either they were used for an entirely different purpose, *or* they may represent an earlier assault on the Church by the enemy. Either way that's one of those issues which would require a lot of research by someone with more resources than myself.
There was an episode of In Search of... once on the Holy Grail legend which discussed an apparent labyrinth structure in the landscape of Glastonbury. The suggestion is that it pre-dates Christianity. What type of rite it was used for, I have no idea. It would certainly be bizarre if it turned out to have any links with a victim sacrificing pagan cult. All those bog men. [eerie horror film sound effects...]
I'll admit that line had me really scared for a few moments... LOL!