OK, so first, I installed 251 base 57:
IOS222 (rev 65280): Stub
IOS223 (rev 65280): Stub
IOS249[56] (rev 65535, Info: d2x-v10beta52): Trucha Bug, NAND Access, USB 2.0
IOS250[57] (rev 65535, Info: d2x-v10beta52): Trucha Bug, NAND Access, USB 2.0
IOS251[57] (rev 65535, Info: d2x-v10beta53-alt)...