As of hrev49248, TeX Live 2014 and LyX 2.1.3 have been added to the Haiku Ports repository!
A word of warning: TeX Live is a mammoth 823MB package, and LyX, whilst not massive, is another 20MB or so. These will undoubtedly take some time to download for installation. Also, upon first launch of LyX, it will appear to not open any windows. This is normal, as LyX is generating a whole bunch of data it needs, which will be stored at ~/config/settings/lyx. Subsequent launches of LyX should be fairly quick.
