Change Offline Name From "Player"?

[Kilyrka]

Every now and then, some of my mates and I will set up a Tekkit server for a small LAN game. We don't have internet for every computer though, only my computer can connect to the internet. (We have all payed for Minecraft) The problem is that when you log in offline, your name is automatically "Player". Normally, this isn't a problem, as I log in online, using my actual user name, and the other person just use Player. But we are planning on having more than 2 people on the server soon, and I need to know how we can change the default offline name. I know that you can do it with this command:

java -Xms512m -Xmx1024m -cp "%APPDATA%\.minecraft\bin\*" \ -Djava.library.path="%APPDATA%\.minecraft\bin\natives" \ net.minecraft.client.Minecraft "yourusername"

But that only works for the normal Minecraft client. Is there anyway to modify this code for tekkit or something?

[disconsented]

You can just apply the tekkit modpack to a normal minecraft jar, from there you can use the normal launcher.

[Crusader66108]

And how exactly would you go about doing this?