Let my preface this by saying I don't really know what I'm talking about.

Ok. I would imagine you would want to use your matched pair of GT44s in a spaced pair config. over the top of the piano, one over the bass strnigs and one over the treble strings.

First, open the top and take off the top and bottom facings.

Make sure that there is some sense of balance in the recording space. Hang up sound blankets and put down carpeting, etc. if it is needed. Move the piano if you have to.

Use the pairs for stereo imaging, use the others for spots and room tones. Just plug 'em all in and and start moving them around until you have the tone you want.

nevermind the recording, first:

move the piano around in the room untill it sounds right
(which is probably not with its back against a wall)

on the shure website you can find a usefull pdf about recording,
it lists all kinds of different techniques

have fun
cheers

Why would you remove the soundboards? Or even move the piano? I'd want to tune it after moving it.

I've recorded my friends 1880 upright grand (cant remember make) a number of years ago with good results. I placed two mics at the top, on the left and right sides, after opening the top a couple of inches and placed one near the floor on the lower front soundboard. I had one somewhere on the back too, I just can't remember. They were 57's right up close, into some 16 bit yamaha digital recording console.

The resulting recording was chubby. I'd say just experiment. Use your ears to find the instruments sweet spots and mic it up.

Keep in mind, I too am a rookie. Just do it. Experiment. I'd just mic the heck out of it, watch for phasing, and keep/throw out what you need later.

You remove the facings to allow more sound to escape and get rid of the woody sound you get from just recording out of the open top.

But isnt the wood part of the instrument and the overall sound that it makes? If you pull it right off, sure it makes things louder, but it also must change the over all sound and feel of the instrument.

I'm just thinking out loud here, and would like to know..

Why open the lid of a grand piano? To let the sound out. Unless it's a very high-grade upright piano, say a Steinway, the facings are just there to look pretty. Most uprights these days are made of woods that are usually of low/medium quality with venier glued on. It's the soundboard that makes the sound.

In the early 20th century the facings were actually carved out lace/lattice work (I think the called it grillwork) to allow the sound to escape.

They don't make stuff like that anymore! It's just too expensive.

My father-in-law refinished pianos like this before he retired, so I had the opportunity to inspect them closely and play them. The tone of most of them was exquisite although the actions varied greatly.

On my very first piano (over 40 years ago!) the entire upper facing tilted out from the top to form the music rack and allowed the sound to escape from the sides. This was a compromise in the 20's and later to the expensive hand carving.

I don't mean to be pedantic, but spend a little time on the history of a subject. It provides valuable insights, is fun, and makes you look smart.