How to fill a large area with blocks using command blocks in MC 1.7.2?

I am building a massive fortress in creative and would like to be spared the monotomy of putting the floor in. I have access to commands and command blocks.

The modded server I am using is for running Minecraft version 1.7.2. I can't update it and it isn't my own server.

There's not an automatic way to do this in 1.7.2. If you're willing to be patient for 1.8 to come out, you can use the /fill command.

1. Go to one corner of your castle and press F3. Write down the coordinates.
2. Go to the opposite diagonal corner in your castle and write down those coordinates too.
3. Open the console, and type /fill x1 y1 z1 x2 y2 z2 gold_block with the above coordinates. This fills your entire castle floor with gold blocks.

or, if you're impatient, you can use the snapshots for a quick access then return to the current version (unless you're doing this on a server)