Granting permissions on SQL Server , to view legacy DTS packages requires EXECUTE permissions to various stored procedures on the msdb system database.
The easiest way to implement , is to create a database role including the permissions. Add the SQL Server login to the database role.
The added benefit of using database roles is it complies with standard SQL Server security policies. Most standard security policies advocate the usage of database roles versus using object level permissions. Read more on How to manage the IS_GRANTABLE security risk
Stored procedures required to view legacy DTS packages
Add EXECUTE permissions to these stored procedures in msdb . The login should now be able to view the relevant DTS packages.