I'm working with Proteus and I'll be needing an IC which has packaging TO-99. This package is not available in ARES. I don't quite understand the data sheet of this package to make it, though I saw a few tutorials on Youtube. How to make out which type of hole is there and all. i.e, which one needs a pad and which doesn't. I'm not able to visualize it and that is what is creating the problem. Can someone throw some Light on this?
I see no reason to suspect that any of the pins are not electrical contacts which deserve a pad, though the connection diagram might show that some of them are unconnected.
The drawing you link shows that the radius of the pin circle is .100 inches.
It also shows that the diamter of the housing is .370 inches, not counting the orientation tab.
While not very clear in presentation, the leads seem to be between .016 and .021 inches in diameter - they seem to show two numbers, one with tighter tolerance close to the package and one with looser further out.