xsi curved trench help

[Oceans14]

I'm trying to model a 45 degree turn in a trench using xsi, but I can't find a precise, clean way to do it.

Hidden/Spoiler:

In the image I've duplicated the first piece and then rotated and manually moved it, but that just seems so sloppy and I'll have to clean it up after merging which isn't ideal. Is there a better way to do this?

[Marth8880]

Model it to be straight, then rotate the vertices of the bent bit around the corner edge.

I suggest taking a look at these videos: http://gametoast.com/viewtopic.php?f=36&t=25943