I don't know if this idea has already been suggested and perhaps discarded:
I have accounts on EU, NA, RU and Asia. At the moment I have to install the mod pack 4x - once on each client - each time I want to update.
Would it be possible to create an install script that allows you to select multiple clients at the "browse" option, and then let the installer automatically update each of the selected clients in sequence?
If you wanted different mod combinations obviously you'd just do normal single installs;
Similarly, the different types of install could still be done seperately;
The final "go to xvm.com" page would not have to be altered, because one visit to XVM can be used to log onto each client account.