Hello Steve,
as far as I know is VBA single threaded and it is not possible to run multiple threads or processes.
I think one way is to code six different VBScript files with your code. Start each from Excel with the VBA command Shell, here an example:
Shell "wscript.exe MyScript1.vbs"
Shell "wscript.exe MyScript2.vbs"
etc. etc. etc.
Let us know if it works.
Cheers
Stefan