Can my employer later add methods of exercise not provided for in the original grant?

Yes. Many companies do this because their original plans consider nothing but cash exercises. For example, your company may decide to add cashless exercises, stock-swap exercises, or net options exercises. This often depends on the administrative ease and benefits these methods offer and the services provided by any brokerage firm or transfer agent that handles these transactions for your company. In addition, depending on your company's interpretation of the legal and accounting requirements, adding exercise methods may require shareholder approval.