Installing gcc without xcode?

Question

How can my students install the command-line gcc compiler into Lion without having to download the entire, huge xcode environment from AppStore?
(up to 2-hour download)

Answer 1

I would consider a different roll-your-own strategy; if you're going to invest in this effort, it's usually best pick your battles.
You're clearly trying to optimize for network bandwidth, but at the cost of an older compiler (Clang is the path forward for Mac OS X, and not gcc) and at maintaining that part of your students' environments yourself, and at dealing with the usual errors and weirdnesses, and at an approach that's not integrated with Xcode; most industry work now arises with an IDE of some ilk. 
Obviously you know your curriculum and your available time here for IT, of course.
Here, I'd move to an approach based on mastering the entire Mac OS X installations, and loading those into the students' systems, and I'd incorporate the standard kits into the master including (for this case) Xcode.  There are other advantages here, too.  If something goes wrong with the student's environment or a disk fails or... you can blow away the contents and reload the master.
For some discussions of mastering and managing your own distributions, see the MacEnterprise mailing list and mailing list archives, among other resources.  (With a server, you can run most of this stuff on-line.  Also hosting Apple software updates via Mac OS X Server and Software Update Services, or via Linux with the Reposado package, to cut down your bandwidth requirements.)
It's also potentially possible to use a different distributions here as part of your mastering; check with Apple around the availability of that.
And if these arem't your school's Mac systems, there's a whole 'nother discussion here around managing the Apple Ids and related on these systems.  (There are some of those discussions on the MacEnterprise list, as well.  Check the mailing list archives, among others.  It's a goldmine for these sorts of questions, and Xcode has specifically been discussed at length.)