As to your question about doing a clean install. I am currently writing this in Lion that was created from a clean install. I tried the various boot loaders out there and they either made Lion hang, crash or actually make my computer hang right at the computer logo screen.
I am a noob at installing OSX on a hacintosh so my method is crude, but it worked. What I did was I created 4 partitions (I have a 2 TB drive). The first partition is my Macintosh HD (blank & formatted), the second partition is Winbloze 7, now the last two partitions are small, only 10GB and 30 GB respectively.
These last two partitions is what helped me do the clean install. On the 30GB partition I installed a very basic installation of SL using the iBoot + Multibeast method (I used the latest versions) and upgraded it to 10.6.8.
I have a backup copy of my Lion install app stored on a USB stick as well as xMove. I copied these to my new SL partition. I ran the Lion installer app and it did the pre-installation prep to my SL partition. I then rebooted back into SL and ran xMove. I used the 10GB partition as the "installer" drive. **NOTE: booting into SL caused KPs, BUT every time I rebooted back into SL it was fine again**
I rebooted into the installer drive and did a clean install of Lion onto my first partition Macintosh HD which was blank but formatted journaled. The installation went smoothly.
Now the key thing is on the reboot I went back to SL NOT Lion. Within SL I was able to run multi beast and install (for my preference) "User DSDT", "System Utility", sound kexts, and "Chimera" on the Macintosh HD. After the multi beast install I rebooted and to my delight Lion booted without any problems! I was also able to copy multi beast to my Lion install and ran it to get my ethernet working. I was also able to erase the two small partitions, join them back as one and use the blank drive as backup for my documents.
As I said, my method for a clean install is ugly but it works.