It is very much possible, pretty much anything you'd like is possible, you just gotta know how to do it. However, since this is a help forum and not a request forum I'm not going to do it for you, so I'm just here to tell you what you need to do.
Your points script will save a file called points.ini with each individual user's points separate. What you need to do with the giveaway is to read the giveaway.txt for every nick is in it, you'll need to know the number of lines for this which should be the first line of the file. So you'll want to write a new number in the file for each person who enters, at first it'll be 0, then 1, then 2 etc.
You'll need to use this number in a while loop to search for the #,.,%line (%line in this case is the $nick presented in the .txt) and evaluate all of these numbers which has the highest.
Then you'll wanna use these values and make an alias which states how high of a chance each point will give you.
Just ask whenever you stumble upon a roadblock and we'll help out. Use the help files for whatever you're wondering about first though, you'll find tons of useful information in there.
