Ah. Well, if you want to use the MCP3008, then I'm afraid you will have to write a library.
However, one of our I2C 4-channel ADCs would be a lot easier, and you'll get 4 channels instead of 1. You can string up to four of them on an I2C bus, giving you up to 16 channels.
12-bit, 4 channel16-bit, 4 channelWe
do have an Arduino library for these guys.