How would I do that?The latest version of the pack (aka 1.2.3) on the FTB launcher is broken as the version of chisel 2 that it is using conflicts with railcraft. Which is causing a crash to desktop when ever you try to start the game or a server. To fix it you need to manually update chisel 2 to either it's latest version or one of it's dev versions.
Edit - Please see this post
Each individual mod in a pack is organized in its own .jar file within the Wanderlust Reloaded folder. What you want to do is:How would I do that?
It appears that they released a official version (2.3.6) with the fix in it already so no need to use the dev version any more.Each individual mod in a pack is organized in its own .jar file within the Wanderlust Reloaded folder. What you want to do is:
1) Download Wanderlust Reloaded v1.2.3 if you haven't already. Allow it to crash on launch, or kill it early with the console. Doesn't really matter.
2) Go back to the FTB launcher and highlight Wanderlust Reloaded (WLR) from the list. Click edit mod pack, This'll show you a list of the mods active and inactive.
3) In the bottom left of the window that opened, there should be a button called "Open Folder"
4) Ctrl+F and look for the Chisel 2 file, it should appear as Chisel2-18.104.22.168.jar
5) Now go here: http://www.minecraftforum.net/forums/mapping-and-modding/minecraft-mods/2254671-chisel-2-2-3-5
Download the latest version of Chisel 2
6) The move the file you download into your mod folder. Delete the old one.
I hope that was clear, but tl;dr you want to replace the old Chisel2.jar with a newer chisel2.jar
Edit: Following Danidas' post, you can download a more-more recent Chisel2 version here: http://coloredlightscore.us.to:8080/job/Chisel-2 v1.7.10-Dev/46/