Anyone wanting to learn how Anglican Chant works as a musical style for the Psalms could look at a couple of introductory webpages.
There is a helpful one on the BBC website at http://www.bbc.co.uk/dna/h2g2/A15716595.
There is a helpful one on Wikipedia at http://en.wikipedia.org/wiki/Anglican_chant, where I particularly like the example given - with a colour-coded musical stave that can be matched up to the text of part of the Magnificat printed in the same colours. Nice.
The great advantage of this method of singing is that it is not necessary to alter the words in order to fit a melody, because Anglican Chant is a style of music that moulds itself to the words. Ideally therefore, the flow and speed of the chant would match the way that a speaker would say the Psalm in normal, careful speech. However, because the chant is musical, there is still melody and harmony so that variations in speed, a choice of major and minor keys, and other such devices, make it possible to match the music to the tone of the Psalm.
There's much more on the internet on this - feel free to post other links in the Comments section below to help readers find other useful resources.