In your comment, you said that you want to do this so you can re-use the method in other forms. In that case, you can make a form that handles ProcessCmdKey, and make Form_Save (and perhaps other forms) derive from that form:
class ProcessCmdKeysForm : Form
{
protected override bool ProcessCmdKey(ref Message msg, Keys keyData)
{
}
}
class Form_Save : ProcessCmdKeysForm
{
}
class AnotherFormIfYouWant : ProcessCmdKeysForm
{
}