Hi fsoria,
I believe the IBCONFIG function on page 5-26 of the NI-488.2 Software Reference Manual has what you need. You can find the link below.
http://www.ni.com/pdf/manuals/370963a.pdf
Please keep in mind that you can't change the system controller on the fly. Instead, you have to do it at the beginning of the program. You can, however, change the controller in charge with the IBRSC function (page 5-69). Hope this helps!
