Program LPC1343 thru USB bootloader with the right FILE format
The file is a straight binary file. So, the first four bytes are the initial stack pointer value, the next four bytes are the initial program counter, and the interrupt vectors follow. As an example, here are the first 32 bytes of a known-good file:

00 08 00 10 99 3c 00 00 21 40 00 00 25 40 00 00
29 40 00 00 2d 40 00 00 31 40 00 00 9a 7a fe ef


The word stored at address 0x1C (seventh word) is a checksum of the first six words. See section 21.7 in the LPC13xx User's Manual for details. For the LPC1343 the file is exactly the same size as the flash: 32768 bytes.