javascript and C# ... Is it possible?

Yeah it's possible, you just have to embed your C# dll on a webpage, then access it through script like you would any ActiveX control. Look at "no-touch deployment" and "C# applet" in MSDN. For example, http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnforms/html/winforms05152003.asp

IM trying to write a program for a game called "diablo 2", much like the pre-existing d2jsp... What i would want is a program core (in c#) that allows scripters to write in javascript in order to tell the core what to do.... check out spidermonkey and ull get what i mean. =\

What do you REALLY want to do? You can use Jscript.net to write your whole application.