Important backup scenario.pak file just in case.
 Use a hex editor to edit the SCENARIO.PAK file, find a line
 containing: 
 
 Depending on which house you chose, edit accordingly
 or edit them all, though this could take a while.
 
 The parts you want edit are the ones that have "Brain=Human"
 in them, this is you. The first two scenarios of each house usually
 don't need to be edited, although they can be.
 Enter a generous amount for credits and maxunits.
 
 EXAMPLE:
 for Harkonnen,
 quota=0
 credits=50000
 brain=human
 maxunits=500.
 Keep in mind that there's about 20 scenarios per house.
 Alot of work, but worth the effort.
 
 Here's how to get the units you want and place the in any scenario.
 Using pctools edit the scenario.dat file in the file you will find all the
 scenarions of all the three houses.
 All the units will be listed along with their positions on the map.
 Change the name of the units to the units that you want.
 Just make sure the new units name is the same lenght as the original
 unit for example:
 
 a) heavy tank to sonic tank(this will work)
 b) tank to devastator(this will not work)
 
 you can also edit the units that you can buy from starport here.