I'll post the main part of the Techni-Craft crash file (see below), but I actually understand what it says. There are also several threads about this error on the internet with explanation what to do. This is not my problem. My problem is, that the TechnicLauncher ignores my attempts to modify the Java Args according to the suggestions in the crash report. That's my question.
Reika.DragonAPI.Exception.InstallationException: ChromatiCraft was not installed correctly:
You are running Java 8, and need to use the JVM argument '-XX:+UseG1GC' or you will suffer memory allocation-related crashes.
Note that you may have to remove other GC arguments, such as '-XX:+UseConcMarkSweepGC', which is commonly auto-specified by launchers.
Current Java Args: [-Dfml.core.libraries.mirror=http://mirror.technicpack.net/Technic/lib/fml/%s, -Djava.net.preferIPv4Stack=true, -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump, -Djava.library.path=D:\ProgramData\Minecraft\.technic\modpacks\mikedu900s-awesome-modpack\bin\natives, -Dminecraft.applet.TargetDirectory=D:\ProgramData\Minecraft\.technic\modpacks\mikedu900s-awesome-modpack, -Xms3072m, -Xmx3072m]
Try consulting http://www.minecraftforum.net/topic/1969694-for information.
This is not a ChromatiCraft bug. Do not post it to http://www.minecraftforum.net/topic/1969694- unless you are really stuck.
at Reika.ChromatiCraft.ChromatiCraft.preload(ChromatiCraft.java:303)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
.....
Whatever I do, the "Current Java Args" stay the same.