Ben Richardson has a post showing how to create user-defined table types and pass them into stored procedures:
Table-valued parameters were introduced in SQL Server 2008. Before that, there were limited options to pass tabular data to stored procedures. Most developers used one of the following methods:
Data in multiple columns and rows was represented in the form of a series of parameters. However, the maximum number of parameters that can be passed to a SQL Server stored procedure is 2,100. Therefore, in the case of a large table, this method could not be used. Furthermore preprocessing is required on the server side in order to format the individual parameters into a tabular form.
Create multiple SQL statements that can affect multiple rows, such as UPDATE. The statements can be sent to the server individually or in the batched form. Even if they are sent in the batched form, the statements are executed individually on the server.
Another way is to use delimited strings or XML documents to bundle data from multiple rows and columns and then pass these text values to parameterized SQL statements or stored procedures. The drawback of this approach was that you needed to validate the data structure in order to unbundle the values.
The .NET framework then makes it easy to pass in an IEnumerable as a table-valued parameter.