When joining the localiser on a ILS approach you want to be stabilised.. on speed, on altitude, on localiser. Depending on your distance from glideslope intercept you want your flaps set one notch below your final flap setting be it flaps 30 or flaps 40. Most landing are conducted at flaps 30 so set the flaps for 25 and be on your manouvering speed.

When the glideslope comes alive lower your gear. Upon intercepting the glideslope add your last notch of flaps and make small power adjustments for VPROG/VAPP speed. This will give you a stable approach which will just require small changes in power. Over the threshold reduce power for VREF speed and hold VREF until the flare. The only thing you will have to worry about will be staying on localiser on glidedlope and on speed.

I flew an ILS approach manually i nthe 747 and posted on youtube. You can watch how it's done.

http://www.youtube.com/watch?v=HB4n8uCPh0I