Re ILS Glideslope 2002

I have been flying the B737/777/747 on the FS2002 and so far have not been able to find out how you can lock the aircraft onto the GlideSlope while doing an instrument landing. Does anyone know how I can do this or if its possible to achieve it?
Im flying the plane into the TMA and as I approach the green glideslope on the GPS and if Im tuned in I thought the acft should just automatically lock and fly me down to within about 50 feet of the runway before I disengage autopilot and go to idle/reverse thrust.
Anyone with more experience that would be able to help me?
Cheers/Steve.

It may be as simple as engaging the approach mode in the autopilot.

There is a button labeled "APR" on the autopilot. When you have placed the aircraft in a position to intercept (within 20-25 miles of the runway, within the 180 degree arc to either side of the runway heading, and at or below the glideslope intercept altitude), and you are sure the NAV1 radio is tuned to the ILS frequency, just press the APR button and the aircraft should intercept and fly the approach.

You also must be sure that the GPS/NAV toggle switch on the intrument panel is set to NAV.