SN74HC4066: May I know how to define the VIH/VIL/VMAX/VMIN when we use Vcc=3.3V ?

Yes; see [FAQ] What method is best used for estimating specification values between those given in the datasheet?

Hi Adam,

You are correct in thinking that you can use proportions between 2V and 4.5V to calculate. To be specific, if you need to find VIH/VIL/VMAX/VMIN levels given between those defined in the datasheet, you would use 70% of your Vcc level to obtain VIH and 20% of your Vcc level to obtain VIL. So, 2.3V and 0.7V respectively. Vmax would become your new Vcc of 3.3V and Vmin would be above ground. 

Thanks!

Alex