You will need to do the following:-

1. Import your custom catsuit OBJ. (No option boxes checked).
2. Open the Poser grouping tool and click the "Spawn Props" button.
3. File export all the spawned props in OBJ format. (No option boxes checked).
4. Clear the scene.
5. Load the original casuit figure.
6. For each body part use the Poser menu Object:Load Morph Target and browse to the relevant saved OBJ file.
7. When all the body parts have had their morph targets loaded go through every body part setting the new morph dial to 1.000
8. Now use the Poser Figure menu and select Create Full Body Morph.
9. Go through all the body parts resetting the morph dial back to zero. (Or use Edit:Figure:Restore:)
10. You can now control your new morph using the new dial that has been created in the BODY parameters.

Though not essential there are tools in the Poser Tool Box that will speed up this process.
http://www.philc.net/PTB_tutorial4-3.htm