It's been so long, I don't remember which morphs I used. And I don't seem to have the SP3 mertail in my Poser library any more.  I do know it was a fairly lengthy process and took a few attempts before I was successful. I think the following is how I did it:
I first created a V3 mannikin with a SP3 morph. To create the mannikin I went to File, Import, Wavefront object in Poser. I then went to RuntimeGeometriesDAZPeople and loaded the blMilWom_v3.obj file, making sure none of the boxes on the Prop import options screen were checked. The I went to Object, Load Morph Target. From the same folder, I loaded the blStephaniePetite.obj file. For a label I probably used SP3. I then saved her as a Poser prop, calling her something like "V3 to SP3."
In Tailor I loaded the V3 to SP3 prop as the figure and the mertail as the dress. (You need to change the filename to *.pp2 when loading the figure, in order to make Tailor see the prop.)  I selected the SP3 morph and had Tailor transfer it to the mertail, saving the result. In Poser I have a set of poses for setting joint parameters on various figures and used the SP3 one on the new mertail, so it would conform properly to SP3. I don't remember where I found the JP poses, probably here on Renderosity.
To add any of SP3's morphs I had to save an SP3 figure in Poser with the morphs injected, load Tailor, set up the morphed SP3 as the figure and the new mertail as the dress, and let Tailor do its thing.
As I said, a rather lengthy process. And I don't know if I remembered all the steps. I think I may have had to scale the original mertail down to SP3's size and save it as a new figure before I got it to work well in Tailor.