Creating Custom SBF file

Ok, im am trying to re-compile a SMG file that i have unpacked with unyaffs.

this is what i am trying to do before everyone starts shouting that you can just use a update.zip

Where i work we are about to start reselling Verizon Wireless under a different name, we buy our phones from Verizon.

i am trying to "de-Verizon" the phone and put some of our own customizations on it ie: Carrier text, boot screen ect...

any way, i need to do this in the least intrusive way so that i can show the AE's how to do it before giving to customer, or can be done by some one else.

The RSD-lite method looks the best, i have already successfully changed the moto logo and go that working, but now i am trying to edit the Carrier Text "eri.xml" in the stock load WITH OUT rooting.

Once i unyaffs the file i can do what i need to do but what steps do i need to take to compile it back into a smg file?

does anyone have a better suggestions for what i am trying to do?

Thanks, this forum has been a GREAT help