This is totally feasible, ImagePlay allows to add your own Plug-Ins. Like this you can also add algorithms which are patented (which I don't know if and how and where SIFT is.)
https://github.com/cpvrlab/ImagePlay/wiki/Plugins:-01-Tutori...
https://github.com/cpvrlab/ImagePlay/wiki/Plugins:-01-Tutori...
SIFT is patented[1] and not free for commercial use. This puts people who want to use the amazing alternative to play around finding alternatives, which are usually either half-baked functionally or simply not as good.[2]
[1] https://www.google.com/patents/US6711293 [2] http://dsp.stackexchange.com/questions/1288/what-are-some-fr...