There are many people that are forced to use a proxy, be it students in shared accommodation or school staff. Following the blog of The Minecraft Teacher I've realised that Minecraft could be used for educational purposes, but most schools have a proxy.
I've so far found that moving the minecraft.exe into the %appdata%/bin folder and creating a batch file with this in should work:
java -Dhttp.proxyHost=hostURL -Dhttp.proxyPort=hostPort -Xmx800m -jar Minecraft.exe
… although I've so far been unable to get this to work.
Best Answer
To be able to play not just the HTTP proxy needs to be added, but also the HTTPS, because authenticating is going through that.
The proper batch file should look like this:
I put the batch file next to my Minecraft.exe and started with this. Works like a charm ;)