Is there a way to get M4/V4 to work in Face Room? 

No, the face room is specific for Poser and needs specific files for the figure, and I understand they are a bit of a pain to produce.

M4/V4 are DAZ products and the respective files are not available for any DAZ figure.

The only thing that DAZ has supported post Poser 4 is the ability to read Poser file formats.  They have always refused to support any feature from Poser 5 or later.

 there is/was a proggy to make face morphs ...........but I forgot what its called  doh...........sorry

There was FaceShop Pro but I have to admit I never really had that much success with it in any version and I tried a few.  Then there is FaceGen but it is on the expensive side.  I think you can also use Blacksmith3D, perhaps someone can confirm that.

 Slingshot the object file into Blender and you have a Full Body Room.
And use projected pâinting to get a new texture. 

Is there a way to get M4/V4 to work in Face Room? 

Not natively, no. The Poser Face Room uses, IIRC, a Facegen algorithm. (So do games, like some of the latter Elder Scrolls series.) Facegen is available, but it's pricey and you must also buy the companion package, which is still more cash, in order to produce faces on custom meshes.

As I understand it, the issue is that Smith Micro can't/won't give creators access to the reference files needed in order to be able to import new mesh coordinates. There are refs for all the standard Poser figures, but in order to use the faceroom with 3rd party figures, they would each have to have their own reference file so the faceroom would know how and which vertices to move and how to map the new texture.

For good quality reproductions, the Facegen developer pack is probably the best targetted solution available. (The dev pack is needed because the mesh (V4/S3/etc) would be "custom.") It is interesting to note, however, that DAZ has successfully gotten Facegen to support G1/G2 figures, natively, saving their users a significant amount of cash, since the Dev pack costs $1000....  I would also say that, with a bit of finagling, it wouldn't be difficult with a devpack version to get Facegen to reproduce whole-body or even radically custom morphs of different objects. IIRC, there used to be instructions on how to do that on the Facegen sight.

If Blender can do this with good accuracy, providing good ref photos were available, I'd love to see examples of that.

I've purchased several versions of Faceshop, in the hope of seeing progress made with that program. Regardless of how good the ref photos are, its results are... just not useable.

Poser Tool Box Face Putty.

Works on any figure.

http://www.philc.net/PTB_page2.php#facePutty

Another way to play with faces: Load your morphs into the head (Morphs++ or any other head morphs you  want to use). The usen the Poser morphing tool on the head. Have it on the Combine tab, not the create tab. Simply pull and push the face into the shape you want. You can turn the active morphs on and off as needed. This is an extremely powerful feature but many people seem unaware of it. The effect is similar to what you get in the face room, but you can use any morphs you own to achieve the face you want. Much faster and more efficient that dialling in the morphs.

In Blender, you need to be careful to import the head retaining the vertex order, and then again to retain the vertex order when you export. Very important.

In Blender you can use proportional editing or sculpting to shape the face. This requires more skill but gives you huge versatility and works very well indeed. You need to do some practicing with the sculpting. DO NOT use dynamic topology or add or delete any vertices. Just work with the vertices you have. A graphics table with stylus is helpful but not essential.

And of course there is the Poser Morp Brush. if you have a Wacom Intuos that surely is an option. The pen reacts sensitive to pressure and that is a world of difference with the on-off behaviour you get with  a mouse. I did try to cheapskate with a Bamboo but no avail.

Go gently, have patience. Use cumulative strokes and low magnitude. This will bring you will a long way. Think of how long it would take to sculpt the face real-life in clay or wax. There is no reason to expect it will be any more quick in 3D. Relative to real life sculpting you have 'healing' (undo) and symmetry but no sensitory feedback from your hands and you see the result with only one eye. You therefore have to change views often to look at your model from different sides.

There is no 'make beautiful face' button. No matter which tool you use the result will depend on your artistic skills.

If you have the Poser Toolbox (which has lots of other great functions), you could change the general shape with the Face Putty, and then refine with the morph brush as FVerbaas describes. If you are working with a mouse instead of the Intuos tablet, heep the magniture very low and work carefully.