Showing Adsense adds between nodes

what I would like to do is add two or three advertisements on all compound pages. Now I manage that by adding an advertisment node every 5 nodes or so (see http://hetziekenhuis.net), but in order to make sure the amount of normal nodes between adverts does not go wrong on other pages (ie categorised pages, see for example http://hetziekenhuis.net/operatiekamer/games : there are no commercials in there, only the ones done by Adsense Injector in the nodes themselves), I had to create a different type of content and make sure it is not categorised.
Adding Adsense to the template is easy enough, but adding them on a regular interval, between posts on all pages requires changing the way the engine works. Is it possible for Adsense to do such a thing as well?

On a side note: I am not exacly sure where to put this request. Maybe this is something that is more easily achievable with Adsense Injector?