In-system programming of the SPI Flash chip
So you're asking how to determine whether a chip can be in-system programmed.

There's a lot of factors to that, but the ones I can think of are:


selective powering: Can you power the memory IC without starting the rest of the system? If giving power to that IC means you power the microcontroller it's connected to, and you have no way of stopping that microcontroller from using the SPI lines you want to connect to to talk to the memory chip, then this can't work. In essence, you'll have a hard time if the memory IC and the microcontroller run from the same power supply, and the microcontroller doesn't have an externally accessible reset pin. Also, if the same power supply powers other components, what will happen?
Side effects of the programming itself: are there other devices on the SPI bus? When the microcontroller is powered of, will these have a chip select line that is deasserted, i.e. will they know that they're not "meant" to be talked to?
Pin direction problems: Now, your MCU is powered off or in reset, but you power your memory and do some communication on the SPI bus. In which state are the pins of the MCU that connect to the memory when powered off/ in reset? Are they shorted to ground, pulled up to VCC? Is it OK to apply e.g. 3.3V to pins when the MCU is powered off, or will it be damaged?