most of the build dependencies are grabbed by the scripts automatically if you're building on debian, but you will have to install wget yourself before running them
sudo apt install wget
To build icecat for armhf either run nativeBuildIcecat.sh if building on an armhf machine, or if crosscompiling on an x86-64 machine run crossBuildIcecatArm.sh
When building natively, I found 4GB of RAM to be too little and needed to create a 4GB swap file. Plenty of instructions online can be found to do this.
Warning: This takes over 2 hours on my armhf machine and a bit longer than overnight on my x86-64 with decent processor and 16GB RAM so get some reading material ready.
Then then to bundle icecat up in an "installer", On an armhf machine run nativeBuildInstaller.sh a compressed binary will then be available at build/installer
if cross compiling, run crossBuildInstaller.sh and find the compressed binary package in build/installer
This step takes only a couple of minutes