With the live cd your only good for a network installation. With a universal cd you can choose to install the whole system from that and use the prebuilt binaries.
Personally I prefer the live cd, and installing from a stage 1 or 2 and grabbing everything from the net. Depending on the way your net setup is that may not always be a good idea to install from the internet. Instead of building while your box is open you may want to fetch what you need first then build. example:
emerge --fetchonly gentoo-sources && emerge gentoo-sources
That will just help a bit not a bunch and if your bootstrapping then it may not be possible to grab the stuff first then compile, I'm not too sure.