2. Now, i get hd5570 work also.
Boot with boothink, and snow leopard retail version, make sure you have update to 10.6.4 and install graphicupdate 1.0.
place the ATY_int.kext to c:\darwin\system\Library SL\Extensions\ and boot with '-f -v' then repaire permission after you start up.（5570 hard id is 0x68d9)
Also, you can install this kext by other tools. just need one kexts after install the graphicupdate1.0.
Thanks to netkas and David.
That's ok, have a good day!
BTW: for my base system is AMD X3 435 +785G, SO I CAN NOT TEST FOR IF IT IS WORK UNDER 64 BIT.