I don't think so... We execute this command manually, so auto-bootrom update was not implemented jet, i think...
1. Copy Boot Rom (.btm) to flash
<hp5120> tftp <tftpserver ip> get A5120EI-BTM-619.btm
2. Upgrade Boot ROM
<hp5120> bootrom update file flash:/A5120EI-BTM-619.btm slot 1
3. Delete actual firmware image (.bin) to make space on flash
delete /unreserved a5120ei-cmw520-r2208p01-s168.bin
4. Copy new firmware image (.bin) to flash
<hp5120> tftp <tftpserver ip> get A5120EI-CMW520-R2220P09.bin
5. Load the system software image and specify the file as the main file at the next reboot
<hp5120> boot-loader file A5120EI-CMW520-R2220P09.bin slot 1 main
6. Check boot loader config
<hp5120> display boot-loader
7. Save configuration (in my case on one switch we don't remember to save but switch boot ok...)
<hp5120> save main force
8. reboot with new firmware image
<hp5120> reboot
If I understand well, you say we can do now:
9. Delete Boot Rom (.btm) from flash
delete /unreserved A5120EI-BTM-619.btm
Is this right ? If so, can you tell me where was put on device the Boot Rom (in which internal memory) at "bootrom update file" command ?