It's very simple to set up, it is!
Firstly, you need to set all the basic flat terrain (Not cliffs, water or waterfalls) to this
Morphable = True
This tag does 2 things, it stops the tile from changing it's height and it stops other tiles from overriding it.
Next, copy the entry for GAPAVE from Tiberian Sun from Rules.ini and Art.ini and paste it over to RA2. Next, make sure the ToTile= tag is set to Pvclr01 so it doesn't look ugly. If you set it to PAVE01, it doesn't edge out the Terrain.
This works in RA2, and YR and allows pavement to be placed on most flat terrain just like in TS!
I did just realize something about this, no weapon, Warhead or anything in RA2 (To my knowledge) causes terrain deformation. The reason they did this is so there wouldn't be terrain deformation.
Bit useless, Westwood...
did you make this?? the game?