Generate Migration from Fluent API or ModelBuilder Conventions/Annotation (EF6)

Question

Is there a way to generate the ForeignKey below in Fluent API on Model Mapping or ModelBuilder Conventions/Annotations? I'm using the EF6.

I was able to create the needed foreign key changing manually after creating a migration! Works as expected... but what i need is creating a automated process for some foreign keys!

.ForeignKey("dbo.Client", t => new { t.ClientId, t.CompanyId }, cascadeDelete: false)

The entire migration:

public override void Up()
    {
        CreateTable(
            "dbo.Orders",
            c => new
                {
                    Id = c.Int(nullable: false, identity: true),
                    CompanyId = c.Int(nullable: false),
                    ClientId = c.Int(nullable: false),
                    Desc = c.String(maxLength: 80)
                })
            .PrimaryKey(t => t.Id)
            .ForeignKey("dbo.Company", t => t.CompanyId, cascadeDelete: false)
            .ForeignKey("dbo.Client", t => new { t.ClientId, t.CompanyId }, cascadeDelete: false)
            .Index(t => t.CompanyId)
            .Index(t => t.ClientId);
    }