There is a subtle difference between TurbineInvoker.eve and TurbineLauncher.exe. I forget which is which, but one can accept command line options. I *believe* it's launcher. Thats the one you want to use if you want to launch multiple copies from the same folder. Either way, you need to use the -usetdm command to force it not check for updates to the files. You really want to launch from the same folder for performance reasons.

I use InnerSpace and ISBoxer as well, and can't recommend it enough.