Hi Roy,
One thing that may help is looking at this app note called MSP-BOOT: www.ti.com/lit/pdf/slaa600 It shows a method for making a main memory bootloader with optional dual-image support like you discuss. I think you may have to do this in main memory depending on how much protocol overhead you have for the bluetooth.
The best option of course would be to make a bootloader in the BSL memory, but that is only 2kB so it depends on how much handling you have to do. You could start with www.ti.com/lit/pdf/slaa450 code for F5438 UART BSL as an example and modify from there, but like I said, it's pretty tight space so if you have to do a lot of protocol handling for your bluetooth this might not fit and you'd have to use the main memory method I mentioned above.
Regards,
Katie
