As long as the custom model is of a human and sticks to the default Valve bone names, I don't see why would the model break the clothing plugin. Maybe raged meant to say that non-human models aren't compatible with the regular clothing items, though I find that rather obvious.
i was under the impression the bodygroups would only work for the tnb models and that the ic items based off changing those bodygroups would only be applicable for those models