I have an RB450G and want to connect 4 Access points to my upstream router. I want to use it purely as a switch but want to configure it properly to avoid bridging loops between the Access Points. I have scoured the forum but have not seen exactly what I am looking for. Assistance is greatly appreciated.

Hi,
I can't see the problem . The access points can't create loops because, if you configure them as AP bridge, they can't registe to each other creatng a loop.
Anyway if you want to be absolutely shure that a loop can't be created in your network, you have to simply enable RSTP on the bridge created inside the RB450 and Access Points:

There are other elements to my network. i.e. There is a switch upstream with other access points. I will be implementing this on those as well.