Cannot allocate memory for multi server instances

This is my first foray into CF 9 multi server environment and I'm having a little trouble.  I have 16GB of memory in the machine but if I set the JVM size (via the JMC) to more than 1GB the server(s) will not start and I get an error about "unallowed heap size".  I looked at the article that tells you how to set up different values for each instance but I just looking to allocate as much as I can evenly to each instance.  How/where do I set the JVM memory?  Also, where the heck is the JMC documented?  I found it only by hunting around the forum until I found a reference to its existence.

Thanks!