you can write Material Effects to .fx files,such as phong.fx,two_side.fx and so on.then,define the materials in your script,
material mat_phong
{
effect = "phong.fx";
}
material mat_2side
{
effect = "two_side.fx";
}
after doing this,you can attach materials to the entites in WED.

You can also attach the .fx to modle's subsets in MED:Edit->Manage skins->skin setting->Effect Setup->load FX.
It's useful for modles those contain multiple subset,It can attach different fx to different subset of a modle.but you can't use A6 material Event and extra texture and so on...
pardon me for my poor English