aspstate is part of the aspnet 4.* framework. This framework is mature and only receiving security fixes. the old scripts are in the C:\Windows\Microsoft.NET\Framework64\v4.0.30319 folder.
you can safely change image to varbinary(max) in the table definition. this is the only change required to the scripts.
if you want to change the schema it is better to do it outside the utility. you can use the above script, or as I have done, create a visual database project from a generated database. you can then edit, and have a deployment package.
you might also want to change to the new async state provider
https://www.nuget.org/packages/Microsoft.AspNet.SessionState.SqlSessionStateProviderAsync/