Attached are what I've found to work well for 4, 5 and 6 channel microphone arrays. I've yet to roll these new revisions into the now old and dated OMT PDF linked in my signature.
For 4 channels using a pair of cardioids and a pair of supercards, check out config 4 on page two of the OMT4 PDF. That one works well in more reverberant rooms as well as in great sounding rooms and outdoors and doesn't require spacing a pair of omnis widely enough (the foundation upon which all other OMT configurations are built) making it more practical for many tapers. Of the OMT4 configurations shown in the PDF, configurations 1 & 4 are the ones I suggest trying.
If serious about playing around with surround (It's fun and rewarding), the OMT5 or OMT6 configs will be most appropriate. Those featuring a rear-facing microphone or pair are obvious choices for feeding the surround channels (a rear-facing pair is best but a single rear mic feeding all surround channels works quite well and much better than most folks expect), but the ones without any rear-facing mics work too by routing the omni channels to the surrounds. You will probably want to route the omnis to to the L/R speakers or sub(s) as well to get sufficient low bass output. Some configs (such as OMT5 #3) require no mixing at all for surround playback, only level balancing, with each mic feeding its own speaker.