The Vietnam 188 client actually supports something like this.
I haven't tested this, but if joymax hasn't broken this feature then you should be able to boot the SR_Client with a different dependency folder using the command line arguments.
The dependency folder inside server_dep will be selected based on the ContentID (local).
It is set from the arguments provided by the launcher "/22 0 0" aka "/{ContentID} {DivisonIndex} {GatewayIndex}". The launcher gets the ContentID from the

.
The creation of the final "server_dep/whatever/" path is part of the initial loading which happens before the server list is displayed so you won't be able to select them based on shards as you intended.
Keep in mind that using 1 or 6 as content id as displayed on the image is a bad idea as there may be all sorts of horrible things hard-coded on them. You should patch them to Vietnam branch equivalents (21,22,23).