I don't think you can share JVM custom properties among multiple servers. However, you can create WebSphere variables (Environment > WebSphere Variables). When you create a variable there, you can choose a scope that will allow the variable to apply to multiple servers. That variable won't work the same as a JVM custom property, so what happens next depends on how the variable is used. If you need to access the variable inside the application, see this link:
If you need it to act like a JVM custom property, WAS might do variable expansion on JVM custom proerties. Say you defined a WebSphere variable named "WAS_VAR_X" and needed that variable to be set as a JVM property named "jvmPropertyX." You might be able to define the JVM custom property with:
Name: jvmPropertyX
Value: ${WAS_VAR_X}
I haven't tried this myself, so if you try it and it doesn't work, reply so I can edit the answer.
