If just the icons, then it's doable with no coding knowledge (but minor editing skills and/or tools are required).
For editing the icons it is sufficient to just replace the icon files themselves with the ones you want to use since PyQt5 opens the files at runtime, so you could also simply download the portable python bundle of Electrum and run it normally after replacing the icons, no compilation required.
If it were a C++ Qt5 program the paths to the icons would be in XML files that need to be compiled to binary, and the program itself also needs to be compiled in that case.