Serious Sam/Steam

I just pre ordered Serious Sam BFE from Steam. Also with the purchase I was able to download Serious Sam the First and Second Encounters. I have played Serious Sam in the past and used mods such as Parse Error. Can I still use this mod on Steam and how would I go about adding it? My old discs were so scratched I couldn't play anymore and now I get this great deal and can't wait to play again!

Remembering back, what were the levels with the spaceship thingy and the football monster guys? Wasn't this part of Serious Sam or am I thinking of another game?

Thanks for your help.

 

Adding mods shouldn't be a problem, the only difference is that games purchased through Steam will be installed within the Steam directory. So if you are manually installing mods, that's where you'll have to place them.

Unless of course the developers have prevented such actions from being taken. Though I doubt it.