I have a video project that I have edited on FCP 4.5, that is coming in at 2 hours and 52 minuets. The client has also asked for some DVD extras on the same DVD. I need to know how to fit all of this content on a DVD-5. I use Compressor when I do my other DVD's. I
You have a couple of options. You can either tweak the bit rate to fit the available amount of time and space you have for the disc at the currect resolution, or you can tweak the bit rate and the encoded image size. Encoding to a smaller horizontal resolution can help you achieve better quality at lower bit rates and thus fit more content on a disc without greatly effecting overall quality of the encode.
If all you need to put on the disc is the movie content, then you could encode at about 3.2Mbps for the video and 192Kbps for the audio and be good. Depending on what type of content you have to encode, encoding at 352x480 instead of 720x480 or 704x480 may be beneficial as well.