MBR not used by rEFIT 0.14, use Boot Sector?

[sounds]

Just to clear the air, yes, I plan to write a native EFI loader.

In the meantime, I used rEFIT 0.14 to "bless" a USB stick and plugged it into a mac. The partition table in the MBR was:

1. FAT16 using most of the drive
2. 20 MB or so HFS+ volume with rEFIT, "blessed" by Mac OS

I put some code in the MBR that basically did INT 10h AH=0Eh to say "Hello world from the MBR." Then it halts in an infinite loop.

I put different code in the FAT16 boot sector that said "Hello world from the Boot Sector." and halts.

It booted fine, but after studying rEFIT's source I can't determine why I'm getting just "Hello world from the Boot Sector" on the screen. I got as far as refit/main.c static VOID StartLegacy(IN LEGACY_ENTRY *Entry) but from what I understand it is loading and executing the MBR.