If I understand you then, yes it;s necessary to injet V4's rigging into the clothing.

In most of the discussions above this is being done outside of Poser in one of numerous "3rd party" applications. It can be done in poser using the Setup room (and there are numerous sources for the procedure to do it that way, including the Poser manual if I'm not mistaken). The 3rd party apps are a bit more efficient, since you can automatically strip out unneeded bones and morphs making a lighter and more efficient cr2 file.

Remember if you are making clothing to distibute (either freestuff or commercially) you can just inject V4's rig including morphs etc, you need to use the developement rig.

Honestly if you are planning to make more than a very few clothing items you should read thru the discussions and look up the various apps discussed then go to the marketplace and look them over. Doing all of your conforming work IN Poser alone is a very tedious operation.