got official 3.72, but want 3.72 hx-2 with 1.5 kernel

I got the official 3.72, but i want the custom 3.72 firmware, is there any way to pull that off?

You're going to have to downgrade using the Pandora's Battery. Then upgrade to the custom firmware. Check the tutorials for a tutorial on how to do it.

is there any other way? i dont really get the pandora thing

No, I don't think there is any other way. Although there are some people on this forum that can make you a Pandora's battery so you don't have to..