it's no way , nintendo haev lock these code in the ARM CPU already, if the logo code have been modify even 1 bit, the ds will refuse to boot. 
sorry for beeing a Pain. Do you know this Info. So I read it there is only Hex 15c urgent. So will it be possible to change 0C0 - 15B and will Checksum in 15c Original?:
0C0h 9Ch Nintendo Logo (compressed bitmap, same as in GBA Headers)
15Ch 2 Nintendo Logo Checksum, CRC-16 of [0C0h-15Bh], fixed CF56h
15Eh 2 Header Checksum, CRC-16 of [000h-15Dh]
160h 4 Debug rom_offset (0=none) (8000h and up) ;only if debug
164h 4 Debug size (0=none) (max 3BFE00h) ;version with
168h 4 Debug ram_address (0=none) (2400000h..27BFE00h) ;SIO and 8MB
16Ch 4 Reserved (zero filled) (transferred, and stored, but not used)
170h 90h Reserved (zero filled) (transferred, but not stored in RAM)
For more info about CRC-16, see description of GetCRC16 BIOS function,
BIOS Misc Functions
For the Logo checksum, the BIOS verifies only [15Ch]=CF56h, it does NOT verify the actual data at [0C0h-15Bh] (nor it's checksum), however, the data is verified by the firmware.
Secure Area Loading Timeout (usually X=051Eh) used to initialize timer counter to (0-((X AND 3FFFh)+2)). (In case of Header checksum error it is ANDed with 1FFFh instead of 3FFFh, no idea why).