Hi TDMoIP
Got exactly the same setup here (MXEE 2 running on a CM 5.2.1 system) - I went for AAR as although got the off-pbx working fine, I read a couple of posts that said people could only get it working to a maximum number of call presentations on the off-pbx station - doing it via aar just uses a TLS-SIP trunk which has the same number of members as your license (of course, there may be other ways but of the 2 docs I had, the "aar" one was certainly a later date/release)...
There are a couple of ways doing it via aar - depends on what you've got enabled on the switch - I find it easier if you have AAR/ARS without dialing FAC enabled but you can normally get round that by using the UDP - I think I know the docs you are on about (have read them several times) - bascially go with the "aar" one - it involves seting up a TLS-SIP trunk (along with its signalling group), a route pattern and an entry in aar - I know all sounds a bit simple - as daft as it sounds, my biggest issue was IP addresses on the MXEE!
Be careful with codecs as well - MXEE only seems to support G.711 (A or MU) - took me a while to figure that one - of course nothing really says that anywhere... If you can post some more details of your denail events and screens of your setup I'll compare them to how I ended up getting ours working... There are probably 2 or 3 other ways of doing it but it works well for us... (I would post screens myself but not in the office at present)
Shaun