There is no election statement for this.  You simply impute the accrued interest as income for the current year based on increase in redemption price since acquisition:

454(a) Non-Interest-Bearing Obligations Issued at a Discount

If, in the case of a taxpayer owning any non-interest-bearing obligation issued at a discount and redeemable for fixed amounts increasing at stated intervals or owning an obligation described in paragraph (2) of subsection (c), the increase in the redemption price of such obligation occurring in the taxable year does not (under the method of accounting used in computing his taxable income) constitute income to him in such year, such taxpayer may, at his election made in his return for any taxable year, treat such increase as income received in such taxable year.