How to add java args to the launcher?

[xarx]

Techni-Craft (4.8.8.3) crashes on my computer when started from the TechnicLauncher (4.347). According to the logs, I need to add a JVM argument to the launcher (because mod ChromatiCraft complians about Java 8). The problem is, that the TechnicLauncher ignores its own Java Args settings ("Launcher Options > Java Settings > Java Args"), see

 

How to modify the java args with which the TechnicLauncher invokes the modpacks? (Techni-Craft used to work on my comp a few months ago without problems.)

Alternatively: Is it possible to start Techni-Craft from the standard Minecraft launcher (and set the java args there)?

[AetherPirate]

Pastebin a log

[xarx]

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.