I don't remember off the top of my head exactly what I did and I need to do another one this afternoon, so... I'll be back with (hopefully) some instructions for a dual boot with SL for you.
Here's where we are so far (I used a 500gb disk for this project)...
(1) set up a 500gb GUID drive and repartitioned it into OSX (250gb, Journaled) and FAT (250gb, MS-DOS FAT).
(2) installed SL using the "via Mac/USB" method (I'll post the link once this is a confirmed method of dual boot...) onto OSX.
(3) booted to Win7RC install disc via USB DVD drive; reformatted the partition "FAT" to NTFS so that Win7 could be installed there.
(4) proceeded with the win install onto "FAT" as per usual
At this point, win took over the bootloader and wanted to run the whole machine. However, booting from the original SL install USB (with chameleon bootloader) gave me the dual (well, it was triple because it also offered the OSX install option that was on the USB) booting screen/access/capability I wanted in my end product. This told me I needed to get chameleon bootloader back onto the boot partition and I'd be good to go. Famous Last Words.
False hope: I thought perhaps simply rebooting the SL install from the USB stick, going to utilities>netbook installer>install chameleon bootloader would be enough to do the trick. Alas, no.
I am currently re-running the whole OSX install to see if that will get chameleon properly in its place.
Re-running the OSX install wasn't any more beneficial than re-installing the boot loader. On a boot from scratch, the HD tries to boot windows but says it needs repair. My next step is to delete the boot partition that windows has taken over and try the OSX re-install, which should bud off it's own (new, chameleon) boot partition as part of it's process.
On a similar note, booting from chameleon on the USB to the OSX partition crawls to load and then results in a kernel panic so my hopes are diminishing for a straight-forward dual boot off this OSX install method (which is too bad, because it's a very neat install).