The majority of business jets up to and including Global Express normally park on DOM5 apron. Normally DOM6 for BBJ and larger. Occasional overflow on DOM4. These aprons are all just to the north of the RW25 threshold.
There are two FBOs which handle private operations on these aprons, and both are within a couple of hundred metres of each other on Ross Smith Avenue. You could walk from the Domestic Terminals in around 15 mins, or get a taxi and ask for Hawker Pacific or Universal on Ross Smith Avenue. Many drivers won't recognise the address, some know it better as "near Krispy Kreme".
Hope this helps.
VI