Check the board, there may be an unpopulated header for in circuit programing via a Dediprog programmer.
http://www.dediprog.com/pd/spi-flash-solution/sf100 (those are pretty common for BIOS developers).
Generally, development is done either via an in circuit programming header, or via a socketed flash part.
A couple words of warning, the system is almost certainly running in 'descriptor mode'. This should be covered in the PCH datasheet. Basically, it allows multiple pieces for firmware to be delivered on the flash part and to keep them separated as if they were on their own flash parts. It also allows for the use of 2 flash parts in some cases.
Assuming a single flash part, they aren't *too* bad to desolder if you can do SMT work (I don't think BGA SPI flash parts are very common anyway). Sockets are a bit trickier, I don;t know any part numbers to refer you to. Fingers crossed there is an unpopulated ISP header.
The HP BIOS may be delivered as a capsule update. You'll want to check the UEFI spec for that. This means that the update may not necessarily be a binary image, just pieces that need to be upgraded. Or it could be that the capsule contains a full flash image, but it will take some effort to extract it from the capsule. Just be careful before you assume it's a full flash image
Once you get the image, it's almost certainly going to look like what is covered in the UEFI platform initialization spec. Both this and the UEFI spec should be free from uefi.org.
There will be a lot of stuff compressed in the firmware image, so a straight binary search may not yield much.
Take a look for borg number one's BIOS tool collection and Borg Number two's BIOS tools collection. There may be newer versions out there too.
IIRC, HP laptops use Insyde's H2O UEFI BIOS. With luck, you can use something in the tools collections to pull apart the flash image instead of having to resort to a hex editor.
Proceed with caution, backup your flash part, and happy hacking!
