Montana Fish and Wildlife Conservation Act of 1998 - Directs the Secretary of the Interior to sell at fair market value: (1) all right, title, and interest of the United States in and to specified leaseholds (cabin sites of the Bureau of Reclamation located in the Canyon Ferry Reservoir in Montana and certain contiguous parcels), subject to valid existing rights; and (2) easements for specified access to such leaseholds.

Sets forth requirements for the purchase process. Grants the Canyon Ferry Recreation Association, Incorporated, the right to match the highest bid and purchase the leaseholds.

Requires the leasehold purchaser to: (1) contribute 45 percent of the purchase price to each of the Canyon Ferry-Missouri River Trust and the Montana Hunter and Fisherman Access Fund (established by this Act); and (2) pay ten percent of the purchase price to the Secretary for deposit in the Treasury. Gives existing leaseholders an option to purchase leaseholds and nonpurchasing lessees the right to continue to lease the property under the same terms provided in existing leases.

Requires the Secretary to encourage establishment of a nonprofit charitable permanent perpetual trust, to be known as the Canyon Ferry-Missouri River Trust, to provide a permanent source of funding to acquire land to conserve fish and wildlife, enhance public hunting and fishing opportunities, and improve public access at the Reservoir and along the Missouri River.

Establishes the Montana Hunter and Fisherman Access Fund in the Treasury for purposes of acquiring land in Montana to improve public access to Federal land for hunting or fishing and enhance public hunting and fishing opportunities through the conservation of fish and wildlife.