The process is fairly simple. You load the desired texture on to Genesis in Daz Studio 4 (in which ever form, V5, M5 etc) Then under the 'Surfaces' Tab, select the icon in the top left corner of the window. Scroll down to Map Transfer. On the top left of the new window where it says 'Template' right click in the box area. Click 'New Template'. On the right side of the window is a list of the surfaces your current 3d model has. Daz have been very helpful here as they have numbered the relevant parts of the map that belong together. So it is then a process of Shift+Left Click each map region in turn. Once you have the whole group selected left click and drag them over to the Template1 that you created. Then change the 'Target UV Map to M4. You will need to have the Template1 selected to alter the 'Template Options' in the lower part of the window. I would advise a quality of 10, and dimensions of 4096. Then select an output directory. Here I would create yourself a dummy runtime in the Poser format. I would see how the texture artist folderised their character and set the dummy runtime up the same. Obviously changing the character name to the one you are converting.
Tip time: DO NOT USE THE DAZ TEMP FOLDER FOR OUTPUTING THE CONVERTED TEXTURES. Because if you close Daz Studio before moving the new textures to the dummy runtime, it will clear the temp folder on closing. Which is a royal pain when you could have spent a great deal of time converting many textures.
What I did to create the Ohi'a Mat's was use a donor set of Mat files (Ovidius) then I swapped out all of the relevant textures to Ohi'a (in The Poser Material Room). Such as diffuse, specular, bump etc. Then I saved a brand new set of Mat files into the dummy runtime. Under the Pose and/ or Materials folders. Using the naming structure that Morris had for the original M5 version.
Please Note: Map Transfer does not convert genital mats between characters. It also makes a mess of the eyelash transparency. So use the Ovidius eyelash texture. Copy it to the Ohi'a dummy textures folder.
Limitations: Map Transfer may cause seams to show in high res textures. I have found this with both Raiya's and Morris's textures. I have found for full body shots the seams should be okay to render. Though portraits will show the seams up. Which will mean cloning out the seams in your chosen art package. Also avoid tattoos that cross seams as Map Transfer will make a mess of the maps.
If you need any further help give me a shout on: firstname.lastname@example.org. I use the same email address for MSN too.
Hope this helps