User managed device id

I'm building a sensor network at home. I have a temperature sensor in all the major rooms, but instead of coding the id while I upload my program I want a physical dip switch under the cover letting me set the id of the device it uses when sending data.

But by working with the ATTiny84 and 85 the number of input pins isnt doable since the number of pins I've got left isnt enough in some cases. I really need a 6P+ dip switch. Does anyone know about a IC or something that solves this task? I would like a single output over I2C or something since I'm currently working on other chips then the 84/85. Anyone with a general tip on how to not tie up all the pins with a dip switch.

You could use an I2C-Port-Interface PCF8574.