Downgrading from 10.8.4 Mountain Lion to 10.6.3 or 10.6.8 MBP Late 2011

Hey folks,

thinking about going back to SnowKitty. (I miss it. A lot.). Currently I have Mountain Lion, 10.8.4.

I currently have a 10.6.3 retail disc, and when I try to boot from the disc, I get the dreaded Three Beeps of Death.
(Tapping Option during Boot, then selecting the disc, or holding C both result in the Beeps).

I have heard that I MUST have the Gray Discs (Recovery Discs) to truly go back to Snow Leopard from my current ML version of 10.8.4.

However, a Tier 1 Apple Tech Support guy just told me (on an official call) that if I

- Go into disc utility in ML

- Erase my main HDD

- Pop in my Snow Leopard Disc

- Boot

that I will be able to install it without any problems.

I kind of wondered about this solution before he told me about it... my obvious fear is that in so doing this, I will again go to boot into

the 10.6.3 disc and get the Three Beeps of Death--but now my HDD will be erased and I will be totally hosed.

Thoughts on this?