I don't have Tekla BIMSight, so I don't know exactly where/how to check in that (click on the red objects and look for a Pset_URL property set).
I put the assumed deliveries in a folder (some random .txt to make it small and a GS guide about the Profiler which was like 104kb) and the .ifc file(s) go to the same level, but really, it's up to you - the sample is the attached .zip file.
You can create "dummy" geometry that refers to a certain view (like planes for sections, floor plans, details), or you can put the paths directly in the desired object itself (I think you posted this to another forum where you mentioned vaults).
To create the label, you can do it in several ways:
1. You can use the IFC Project Manager if you like editing IFC properties directly: you could attach an IFCLabel to the project (create a custom Pset or find the "appropriate" place for it), or you can put it at an object level. I'm not sure which one would be "correct", but I'm not familiar with your deliverables at all.
2. A more structured approach would be to use the IFC Property mapping: first you need to create a "regular" ARCHICAD property (make it a 'String' and available for the desired classifications), that you can map to the IfcLabel. If you use morphs only, for instance, you could put the Pset to the IfcBuildingElementProxy class, which is otherwise not used (ideally). This last option has the benefit to export a schedule with your placeholder geometry, fill up the necessary paths, and import back.
The benefits of this approach: as low-tech as possible, they can use whatever PDF/spreadsheet viewer they like. You can also link to images, as-built or before the project state, etc.
The disadvantages: if you/they break the file hieararchy, the links break too. To make it crossplatform, you can always create a File path - Win and File path - macOS/Linux field. It's also not that fancy looking.
This is what I have in mind right now. Something like this could work? (I created it on Windows, so \ and / can cause a problem with macOS - let me know.)
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