For 1.2, builders could be given(or restricted to, depending on your way of looking at it) tiled building. For example, building structures in RTS' such as Command and Conquer, and Warcraft/Starcraft both use a system of tiles to show where you can build, how far you can build from your base, and showing you where you can't build. Building structures in Tremulous can be a tedious process because of the pinpoint accuracy required for placing structures on map geometry(and even moreso if you're a perfectionist like me). If building were locked to a uniform grid, then builders could actually build faster because they know where they can build based on color codes, and buildings are snapped to a grid.
Here is my concept:

The Reactor generates a power field(as it does now) that buildings must reside in in order to work. Tiles give players a visual representation of that, and are shown when the builder decides to place something. Red tiles show where you can't build(for example, out of the power field/halfway inside map geometry), yellow tiles show where buildings already are, and green tiles are shown for where you can build. tiles would glow underneath the structure you are placing(under the hologram) to show you where you are building.
Obviously this would require some calculation in q3map2 and thrown into the BSP to work(with a modified BSP structure), or it could be calculated at load-time on the server.