You're going to need to post your ECX question(s) on the Corona-Bytes forum, we don't support other software here in that respect.
For the 1.2.3 models, put them in the appropriate half-life/esf/models/player folders, e.g. half-life/esf/models/player/goku for a model to replace Goku.
For 1.3 you just need to cleanly install it into the correct Steam folder (half-life). You might want to go into a bit more detail about the problem though.