Compiling the MULTI-Module firmware is not overly difficult, even for a newcomer to embedded code. All of the configuration options are contained in a single file, which is documented with comments.
At a high level, there are four steps:
Step 1: Download the MULTI-Module source code
Step 2: Install and configure the Arduino IDE tools
Step 3: Edit and compile the code
Step 4: Upload the compiled code to the MULTI-Module
The full documentation for each step can be found on the MULTI-Module GitHub repository: