The info is put into the Aircraft.cfg file and uses info in the effects folder and will look like this:

[SMOKESYSTEM]
smoke.0=5.00, 5.00, 38.00, fx_smoke_rx
smoke.1=5.00, 5.00, 18.00, fx_smoke_rx
smoke.2=5.00, 5.00, -18.00, fx_smoke_rx
smoke.3=5.00, 5.00, -38.00, fx_smoke_rx

that is the set up for a C-130. If you go to one of the big FS web sites. Avsim.com, Simaivation.com and Flightsim.com and do a search for smoke sysem under the FS2002 aircraft, you will find a lot of hits.

Basicly each line is for one engine
first # is the engine number, the next three numbers are the coordinates of the rear of the exhaust, and the last part is the effects file thats being used.

just experiment with it, just BACK UP YOUR FILES FIRST!!

Chris