After 4 days of researching and testing apps from various sources, I have arrived at an interim solution for getting SKP,KMZ or DAE content into Poser, as OBJ imports. Please note that my use is non-commercial private projects only. If you are seeking a cheap and dirty way to use these formats in Poser for commercial work, sorry, mate, no go. Installation and knowledge of how to use freeware 7Zip archiver/unarchiver is required.
1. Get and install MeshLab ( free, but must credit developers and inform them when used ).
2. Get and install Google SketchUp (Free version).
(Note that while there is an OBJ exported plug-in for Google SketchUP, it does not always produce a complete OBJ model, so I don't rely on that plug-in.)
3. Get the content you want from the 3D Warehouse.
Choose the Collada (DAE format), Google 6 ( SKP format), and GoogleEarth4 KMZ versions of the models, where possible.
4. Launch Google SketchUp. If using SKP model, open the SKP model. Export as 3D model GoogleEarth4 KMZ. If you already have the KMZ from the 3D Warehouse download, start from this step.
5. Unzip the KMZ file using 7zip, allowing 7Zip to unzip to folder with hierarchy intact.
6. Get into the new subfolder called model, and look for the file with DAE extension.
7. Open that file with MeshLab. If the model looks like it did inside Google Sketch, save as OBJ and allow the references to textures to be written into the model as well. Best to save into same folder as the DAE file. If you already have the DAE file from 3D warehouse, start at this step.
Sometimes, the DAE produced from the SKP will have missing parts. In this case, do this:
a) open the SKP file in Google Sketchup. At the top menu, click Window to get the drop-down menu.
b) click Components
c) in the pop-up components window, select In Model at the option area.
d) right click on each of the icons shown under that area. A pop-up menu will appear. If Select Instances option appears, choose that and save as in a folder of your choice ( will save out an SKP of the component). If Select Instances option is greyed out, just simply Save As.
e) Still in Google SketchUp, open each such newly saved SKP file, and export as 3D model (use GoogleEarth4 KMZ option), again into folder of your choice - I recommend the same place as the SKP files produced from previous step.
f) Quit Google SketchUp. Follow step 5 onwards from above.
Once you have all the OBJs out, launch Poser and import the OBJs. In the case of individually-exported components, you need to re-construct the model in Poser, ouch.
Some of the models have many parts. I suggest you use Hierarchy Tab in Poser to drag the second part onwards under the very first part, so that they are all parented to the first part. This makes rotation, translation and scaling a whole lot easier inside Poser.
Check textures settings in Material Room, adjust as necessary.
Save as Prop.
Takes a bit of work, but hey, you wanna use free stuff, you gotta DIY a bit.