Yea, I looked into Crystal. It would be possible to create 255-teamed invisible icons nodes and spawn them. But you're right - nobody ever pathed XMP, and that means that foreach AllActors(class'NavigationPoint', NP) will give only very few places, usually only vehicle spawn points... Too bad, it seems it's only possible in UTXMP.
And no, ArtifactPickup aren't only dropped artifacts - if they were, the class would be declared as notplaceable. Those classes are used for dropped artifacts, but they were not intended to be used that way... Like I've written, Alpha XMP had artifacts all over the world, placed like ArtifactPickups, which came directly from Unreal II.