Ok, I probably shouldn't be commenting on any of this stuff, because I am WAY out of date with Gamestudio multiplayer (I did a lot of testing early on with A6 multiplayer but haven't messed with it lately). HOWEVER:
You should to be able to run both the server and client pieces on a single pc at the same time. Just start a server up with -sv (or -sv -cl if appropriate) and then start some clients up using (-cl). This will work fine for basic testing.
However, since you are not actually going out over a network, you can get fooled into thinking all is well with your game when in fact it might not be the case. This is because the biggest enemy of Multiplayer games is network latency and bandwidth issues, and you won't experience either testing this way.
If you are wanting to stress test your game under a simulated network load (ie creating latency and bandwidth issues (i.e. lab problems)), AND if you have the pro version of gamestudio, you can use the network simulator for directx. Use the -sim command line option and the 'DP8Simul.exe' program available with he directx9 sdk from microsoft. Not sure if this option is available on A7 or not.
