I could use diskutil to shrink the partition and then create a new partition, and copy the iso image (via dd) into that partition, and then boot Linux from the internal HD and do the upgrade.

I dual boot with debian sid and winxp. So i resized by winxp fat32 partition to free up somespace and that went fine. However, when i rebooted i can go into windows fine via lilo, but not into ...

If you give it the existing partition, and you already have other Linux distributions installed (and perhaps Windows), it is going to wipe the EFI boot files for everything else.

A review of what EFI boot (UEFI firmware) is, how it works, how it interacts with Linux installations, and a few tips and personal experiences on how to configure and maintain it.

GParted Live boots quickly, and handles virtually any partition type, including nearly all Linux, OS X, and Windows types. Graphically, GParted Live is primitive.

Vincent Danen goes over the basics of using the standard dd tool to back up and copy partitions and drives.

To fix Failed to format selected partition, Error 0x8004242d while formatting drives on Windows 10, you will need to carry out these steps!