OK, if you want to use excel in that way, as a sort of intermediate visualisation of the profitability, then I guess you could do it. There are API commands to let sgminer change pool so if you should write some code that reads your instantly updated excel sheet and sets the miner. If you already have code to read the API from pools and exchanges and put that into excel than the other way around to sgminer wouldn't be that difficult. Just read the docs that come with sgminer about the API commands.