The attached article may help you with setting English texts to psalm tones.

I have posted it previously, but I cannot find it in the archives; so I am attaching it here.

I heartily endorse Bruce's guidelines, and have followed them rather closely in the setting of verses for my collection of responsorial psalms.

Thanks, everyone, for your feedback. Very helpful.

Bruce, I'll be slowly digesting your excellent article over the next few weeks as I have much to learn.

Have read Sunol's chapter on psalmody which isn't bad... Can anybody think of other resouces on Latin psalmody that might be helpful? I'm making my way through the Rossini book for priests at the moment too.

Palestrina,
I also recommend spending a good amount of effort to become familiar with the pattern of the Latin psalmody, both for its own sake and to learn it well before adapting it to English. Try learning the Magnificat and the Sunday Vespers Psalms in all the modes--I think they're in the Liber. Learn with your singing voice, not only with your intellect, how the different tones handle the accents. Not just a few times, but until they are very fluid, maybe even memorized. Listen to psalms sung by other groups or on recordings. All this will help in adapting the Gregorian tones to English. You can even make them part of your daily prayer.

Regarding the Anglican "Manual of Plainsong", it may be worth noting that there are at least two editions, that of 1902 and that of 1951. The 1902 edition makes more use of abrupt mediations. I am no plainsong scholar, but it would seem that the introduction to the Manual at least addresses all the important points about adapting the psalm tones for English; no doubt those more knowledgeable may be able to point out flaws. The tonary they use is that of Sarum, which is not quite the same as that of the Liber Usualis and other recent Roman books.

It may also be worth looking at _The Psalms and Canticles at Mattins and Evensong pointed to the eight Gregorian tones from the Sarum Tonale_ by the [Rev.] G.H. Palmer, Wantage, St Mary's Convent, 1963 (if you can find a copy). This also includes an introduction describing the principles of adaption. The psalter text is Coverdale (like the Manual), and includes pointing for every psalm to every tone (unlike the Manual, which rather arbitrarily chooses one particular tone for each psalm). Obviously one needs all tones if the psalm is to be used with a variety of antiphons.

There is no doubt that the 1902 Manual is usable; my own (Anglican) church uses it every Sunday. Whether better adaptions are possible I don't know, nor do I know how good modern Catholic translations are for chanting.