No, the pistons and rods in the 99 & 01 engines are not forged. However, the crank is.
Because of their lack of forged internals, the 99/01 engines, in stock trim, are not up for the punishment that the 03/04 engines are better suited for (ie - supercharged conditions). There have been a few stories of people with pre-03/04 engines running into problems under boost, because something was bound to break. Naturally, those folks have had to endure a rebuild. There's no way to say that your engine will last "X" amount of miles before it bites the dust...it always varies.
The *ideal* scenario would call for a built engine (forged goodies) & then adding the supercharger/forced induction, along with a safe (dyno) tune, preferably by someone with past experience/knowledge.