Morph Target Tutorial
I'm going to assume you have already read the Poser 3 advanced manual from the MetaCreations website. This tutorial is aimed at jumping the hurdles that are particular to using 3D Studio MAX.

You MUST use the OBJ files provided in the runtimes\geometries folders. Don't try to export a figure directly from Poser3. When Poser loaded it in from its libraries it moved it a little in all three directions. Therefore if you export it, the object you export has been offset, which is a no-no for morph targets.

MAX V1.1 Users Only: Grab the OBJ Import and Export plugins from HABWare They have V2.0 versions of these plugins as well, but MAX V2.0 users tell me that V2.0 comes with OBJ import/export plugins that work fine. Also, if you had some other inferior OBJ import/export plugins previously installed, remove them before installing HABWare's, or MAX will display both, and you won't know which is which.

Import the OBJ files from Poser3\runtime\geometries. If you are using Poser 3 figures instead of Poser 2, you must use the newXXXFHi figures and not the XXXXHi ones. I had originally mistaken Hi to mean P3, but its the 'new' you need to look for. The HABWare plugins are nice in that they let you selectively import only the part(s) you want, a smooth feature for morph targeting! If you are making a morph target for the head, get the head only, this should include the teeth and tongue, but not the eyes. Be forwarned, the head from one model may not be exactly the same as the head from another, even though they look identical.

[Optional] I like to immediately export the object and add it in to Poser before making changes. If you can spin the dial up to 10 and the part doesn't move, you know you've got a clean start for your morph target. If Poser either gives you an error telling you it doesn't have the same number of verticies, or the objects starts to get funky when you spin the dial, you know there's something wrong in your setup.

Make your morph target. NEVER move/scale/rotate the object as a whole. Poser OBJs use a very tiny scale compared to most objects. This does give MAX and some plugins a little trouble, at least my MAX V1.1. It won't let you zoom in quite as far as I'd like sometimes, etc. When making morph targets my favorite modifiers to use are Edit Mesh, especially in conjunction with Volume Select to localize changes, Push, and Buldge. Also remember a little goes a long way in morph targets. What I mean is once you've added the morph target in Poser, you can spin the dial past 1 to get more effect than you modelled. You can also spin into the negatives, which might be useful in special circumstances.

Save out the object with HABWare's OBJ export. You will have to uncheck the rotate coordinates checkbox. Leave everything else on the default setting.

Inside Poser double-click the part you want to morph, click the Add Morph Target button, where it will prompt you for the file and a name for the dial. Be careful, you cannot undo this operation, nor delete the dial once you've added it. You can however set the dial to 0, which will remove all effects from the morph. When tweaking a morph target I don't even bother changing the name from 'shape,' since the last added morph will always be the topmost dial. I just set my previous attempts to zero and keep adding new ones until I get it right.

ADVANCED USERS

There are cases where you have made changes to an object inside Poser with the parameter dials, and that's what you would really like to start with as the basis of your morph target. What you can do is export that model as an OBJ, even though I told you earlier you shouldn't. Inside MAX import both the original piece and the new one you just made. Delete all other body parts from both models. If you didn't use the scale or taper dials, the center of the part shouldn't have moved. Use the Align tool to align the new part to the original, careful not to do the opposite! Inside the dialog check all three coordinates, X, Y, and Z, and also check center and center for both objects. This should snap the modified objects origin to where it should be. If they don't line up perfectly, zoom in as far as you can and move the new one as close to the original as you can. Check all three directions! Delete the original object, and you'll be ready to make your morph target.

ADDITIONAL NOTES:

I had a lot of trouble at first getting morph targets working with MAX. This is because Poser OBJs have a couple of pecularities about them. First, they use carriage-returns instead of linefeeds, so a lot of tools/plugins crash when loading them. Second, they use a very tiny scale, and a lot of tools don't handle enough decimal places and/or the exponential notation occasionally used, correctly. The first one you can get around by loading the OBJ files into a text editor and resaving them. The second one there is no getting around, you just have to find tools that are robust enough to handle it.

Do NOT bother getting OBJIMP.DLI by Jonny Ow, available from 3D Cafe. This plugin is inferior to the one supplied by HABWare. It will also crash when loading Poser OBJ files, unless you have converted the carriage returns to linefeeds.

Do NOT bother getting Crossroads This tool will work, but only sometimes. Other times your morph targets will be mysteriously goobered. I suspect it's choking on the small scales involved.