Claims are a quasi-legal kind of thing, so perhaps some of the legal concepts around property rights could be of use, particularly The concept of Adverse Possession also known as squatters rights.
http://en.wikipedia.org/wiki/Adverse_possessionBasically it boils down to "If you violate someones property right long enough without being challenged then the absentee owner claim can transfer to the squatter". It exists as part of English common law to protect people from centuries old land-claims (many quite fuzzy) that could rob the work of those who have actually maintained/improved the land. The legal codes vary but generally they require the squatter to be using the land as if they were the owner (living their & improving it) and to have done so in a continuous, exclusive and obvious manor without legal challenge by the original owner. In some jurisdiction it is permissible for the squatter to know of the original claim and for them to intend to take the land by this method, so long as they fulfill the other requirements and accumulate enough usage they can take the claim. Another key principle is that if one has the permission of the original owner they are not able to claim the Adverse part of Adverse Possession. Finally the same principles can create 'easements' when someone is doing a more limited activity (such as passing through) on a regular basis they can get the right to continue doing so without nullifying the original owners claim.
Given all this I think the most straightforward way to implement this would be with scents. You only leave scents when your action is 'hostile' (uninvited) and they decay naturally after a time reflecting the fact no one is challenging your activity. When scents decay-away they should build 'squatters rights points' (SRP) specific to the person who left them on the claim. Accumulating enough SRP can eventually result in taking over the claim completely. The original owner should be able to remove the rights build up very easily, they can track scents which will prevent any rights from being awarded and immediately knock off a large but limited amount of the SRP. Squatters Rights also decay on their own and that is greatly accelerated when the original owner is on their land, also the maximum gain rate for SRP is capped such that it would take at minimum weeks to take a claim. Also Squatters Rights could be divided into levels, trespass, theft, vandalism, each stage counts only that type of scent contributes to rights and once the squatter advances to the next level they cease to leave the lower level scents, upon surpassing vandalism level the squatter gains full ownership of the claim (perhaps having to expend LP though).
I observed a situation in game that was very much like this. A palisade-ed village had been abandoned but the owners claim remaining. A new group took up residence their and simply lived their leaving huge numbers of scents all the time, such that I experienced significant frame-stuttering when every I went their with Tracking turned on. Under this system they would gain ownership simply by doing what they were doing naturally and the original owner could have prevented their take over simply by continuing to use the village as he had originally. No jumping through hoops or new mechanics or special rituals requiring the blood of virgins, just a logical extension of the systems already in place operating mostly in the background.