The forum thread says to smash the potion to set a warp point. To me, smashing is placing it on the ground then punching it, or holding it in hand and throwing/dropping with Q key.
The actual way to set a warp point is to right click the potion after it's been placed on the ground. I don't think it's intuitive, and the mod does not indicate in any way that the warp point has actually been placed. Oddly, it does indicate when using a second potion to warp to the set warp point.
The UI is also broken in unified_inventory to where the background boxes don't match up with foreground inventory items.
TL;DR: I appreciate the concept but there are some broken things and I don't think this is easy enough for players.