Since you are using an old version of VectorCAST the best way to do this is to create a test case and put it in a compound test case. Then set the iteration counter in the compound test to 1000001. This will run the test case 1000001 times and will create the condition that you need to cover the "if" statement.

If you were using a newer version of VectorCAST (6.4 or above) you could use Probe Points to set the local variable directly.