How to do boot in the two patition driver?

I have a boot image and USB Mass Storage Device(256MB).
If I make one patition and “dinit -h -R -f my.ifs /dev/hd10”
It can boot normal!
But now I want to make two patition on the driver.
And one patition is for boot , the other is for windows xp OS

How does I do boot on the two patition in one driver?

I am sorry for my all QNX friend! The last message "patition " is "partition"