GPIB and VB6

Hi all.
Here my problem: I have a program written in VB6 which controls, by a GPIB, 2 engines.
Now I have 2 questions: 1) the commands to control the movement of the engine are something like variable.PositionTo, variable.MoveToward etc.
I couldn't understand where is the definition of the command and why the variable is declared but without a type, it's empty.

But the real problem is that I'm sure it's possible to move these 2 engines in the same time, I mean, you can give a position to the first one and in the meanwhile it will reach the position you can give another position to the second one and see both of them move.

I'd like to do the same with VB6 but for now I couldn't. I have an instruction like "x_axis.MoveToward" and "y_axis.MoveToward". The problem is that the engine on y will not move if first it's not finished the operation on the first engine.

I hope you understand what I mean.

So, someone who can help me?

Thanks in advance for your time.