The latest mLinux firmware for MTCAP is 3.3.9. http://www.multitech.net/developer/downloads/
You will find Node Red under pre-built packages.
http://www.multitech.net/mlinux/feeds/3.3.9/arm926ejste/node-red_0.15.3-r0.0_arm926ejste.ipk
If you need an admin GUI, you will need to install AEP instead. If you have flashed mLinux over AEP, you will need to contact customer support.