This is how I start the engines on the C-130 using External Power:

1. External Power - Press [E] on the Simicons Panel
2. DC Power Switch - Eternal (OH Lower Panel)
3. AC External Power Switch - External (OH Lower Panel)
4. Co-Pilots AC Instruments - External AC Bus
5. AC Inst & Eng FVM Cont - External AC Bus
6. Eng Fuel Enrichment - Normal (usually set there by default)
7. Oil Cooler Flaps - Automatic
8. Temp Data Control Valves - Auto
9. Air Start - All Engines (sometimes the some/all engines will start at this point)
10. Eng Starter Switch - 2 (sometimes I need to hold the switch for a couple of seconds for the engine to start, and sometimes just a simple click and instantly releasing the switch and the engine will start)
11. Eng Gen - Reset, then ON
12. Repeat steps 10 & 11 for Engines 3, 4, and 1
13. DC Power Switch - Battery
14. AC External Power Switch - Off
15. External Power - Press [E] on the Simicons Panel

That should be it. Let me know how it goes for you.

Note. Most of the above is done on the 2D panels, but it also works for me using the 3D panels in the VC (with the exception of the External Power). I also sometimes use the ATM for engine start on the C-130.