I acctually meant for you to load the "B-52 Cleared for takeoff (KNKX)" saved flight (which is added during the installation of the CS B-52):
At the FSX start screen, select LOAD, search for Â-52 Cleared for takeoff (KNKX) (I know. It should be B-52 Cleared for takeoff (KNKX), but this is how it is saved in Documents\Flight Simulator X Files folder for me during the installation of the B-52).
This will start FSX with the B-52 and hopefully the engines already started.

If this fails, then perhaps the B-52 didn't install completely. Turn OFF your Anti-Virus program, then reinstall it.
Another thing. Your AV might have deleted an importanat file for the B-52 after seeing it as a false positive for a virus (often a file might be seen as a Trojan).

Here is a list of all the files (there should be 26 files) that you should have in the FSX\SimObjects\Airplanes\CS_B-52\panel folder:

Captain_sim.b520.A01
Captain_sim.b520.A14
Captain_sim.b520.AP
Captain_sim.b520.B12
Captain_sim.b520.BP
Captain_sim.b520.CP
Captain_sim.b520.general
Captain_sim.b520.icons
Captain_sim.b520.L11
Captain_sim.b520.L13
Captain_sim.b520.L19
Captain_sim.b520.L25
Captain_sim.b520.L36
Captain_sim.b520.L38
Captain_sim.b520.L43
Captain_sim.b520.L49
Captain_sim.b520.L50
Captain_sim.b520.LP
Captain_sim.b520.NDL
Captain_sim.b520.OH
Captain_sim.b520.P20
Captain_sim.b520.RP
Captain_sim.b520.sound.gau
Captain_sim.b520.sys.gau
Captain_sim.b520.terrain.dll
panel

The first 22 in the list are cab (.cab) files, and the panel file is a cfg (.cfg) file. You probably don't see the file extensions because these are turned off for common files (by default) in Windows.
If any are missing, I would expect it to be the Captain_sim.b520.sys.gau file, because that is the xxx.sys.gau files in Captain Sim products are the most commen ones to get flagged as a false positive by my AV.
If a file is missing, go to you AV virus Chest/Vault, if it's there, select it, then choose to restore it and add it to the "exclusions" list so the AV won't remove it again.

I hope this helps solve you engines not starting problem.