You can put LEDs in the DRLs, as I've done it and provided you get a dual brightness bulb (ie: that properly replaces the 21w/5w filament original), they will also dim when the headlights are switched on.
On my 4x4 the access for the DRLs is from the engine-bay, down low. A simple twist off cover and bulb mounting. I like the look and they are nicely bright and visible.