passing a comma delimited list into sql server

I need to create a stored procedure that will take 2 dates and a comma delimited list as parameters.  For example  

Create Procedure Test  @date1 datetime, @date2 datetime, @stores varchar(300)

The parameters will come in like this:

'10/1/2013','10/2/2013','300,400,500,600'

In my stored proc I will need to say

 where store number in(the values passed in as @stores)

I won't know in advance what values are going to be passed in @stores.  

Does anyone know how to put the values passed into the In() function?

Thanks.