Scaling the outline mesh would have to be done vertex by vertex, and that wouldn't be acceptable for realtime. Though if you wanted to waste the video ram you could preprepare a few widths, each half the size of the previous and switch as objects move into the distance. But that would only work if you used two seperate meshes. Unless maybe you had multiple surfaces and used alpha... Hopefully you wouldn't get a surface hit for surfaces with alpha 0.
As for antialised lines, they'll be antialiased if you have full screen antialiasing on. Otherwise, you're out of luck. Why would you want the lines to be antialised if your polygon edges aren't though? It would look weird.
If you want to make a cel shaded game which doesn't just use the mesh outline method, what you really need is pixel shaders. So maybe you'll have to wait for Max3D to come along. Then you'll be able to get exactly the effect you want.
As for antialised lines, they'll be antialiased if you have full screen antialiasing on. Otherwise, you're out of luck. Why would you want the lines to be antialised if your polygon edges aren't though? It would look weird.
If you want to make a cel shaded game which doesn't just use the mesh outline method, what you really need is pixel shaders. So maybe you'll have to wait for Max3D to come along. Then you'll be able to get exactly the effect you want.