I'm not sure i understand your question.....
By "PXI BOX" i'm assuming that you mean a PXI chassis with a PXI controller (which is running on windows).
If you have already developed an application on another system..then you can copy this program on the controller in multiple ways
- Put the program on a USB stick
- Connect to the PXI controller over ethernet.
- Write a CD and use a USB CD drive to copy the contents of the CD.
I can think of some other "Rube Goldberg" ways...but lets not go there 😛