installing on "extended partition" while preserving OS X

[Henry <nbsd4ever%gmail.com@localhost>]

I'm trying to install NetBSD 7.0.2 on a MacBook Pro, but keep OS X.
It should be possible, but trying to install from the install CD
TOTALLY destroyed the guid structure.  Fortunately, I was able to
reconstruct the partition structure, although I ended up having to
re-format the EFI partition using newfs_msdos in OS X Terminal.  Although
I lost the Apple *.efi, I was able to re-install the rEFInd bootloader,
which I was planning on using anyway.

After restoring it, the partion scheme looks like the following
(gpt show disk0):
      start       size  index  contents
          0          1         PMBR
          1          1         Pri GPT header
          2         32         Pri GPT table
         34          6
         40     409600      1  GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B
     409640  100555104      2  GPT part - 48465300-0000-11AA-AA11-00306543ECAC
  100964744    1269536      3  GPT part - 426F6F74-0000-11AA-AA11-00306543ECAC
  102234280  139898408      4  GPT part - 49F48D5A-B10E-11DC-B99B-0019D1879648
  242132688    7815024      5  GPT part - 49F48D32-B10E-11DC-B99B-0019D1879648
  249947712     121935
  250069647         32         Sec GPT table
  250069679          1         Sec GPT header
Partition index 1 is EFI, 2 is OS X, 3 is recovery disk,
4 is NetBSD ffs, and 5 is NetBSD swap.

Weird is, rEFInd seems to recognize the NetBSD partition, but if I
click on the NetBSD icon, I get the message: "No bootable device --
insert boot disk and press any key".  Judging from the font and white
text on black, I suspect the message is coming from [something] NetBSD.
I'm pretty sure all the binary sets were installed on the specified
partition 4, and more than likely are intact.

Is there some way to get NetBSD to boot without messing with the EFI
partition?  (Or even using the EFI partition, but not formatting it
or changing the type from efi.)

Thanks,

Henry