As far as I’m aware there is no native support (I could be wrong).

I have seen mention on some sites that people were able to build a TXAA solution into a material and use that in the post process.

Does anyone know anything about this?

Edit: I see there is a bAllowTemporalAA in WorldInfo.uc. However I see no mention of it in the docs: UDK | PostProcessAA

I recall there being some code about it but when I tested it, enabling it in the worldinfo and the related console commands only achieved the jitter associated with TAA (with a controllable depth range) but never the actual behavior of using that jitter and making something useful with it.
I believe there was also some TAA shader code in the shader files. but all in all I just never could get it to work.
I suspect Epic never fully implemented it before moving to UE4, but I have a vague memory of some people on UDN discussing it and talking as if they actually had it working

Hmmm interesting. It sure would be nice to do something about the “shimmering” pixels when running at low resolutions like 1080p.