i bought a lighting fixture that says that its wires are rated for 90 deg temp at least and that most houses built before 1985 only have wiring rated for 60 deg and if so contact an electrician. well my house was built before 85 and so i need to know what i would have to do myself to resoolve this

The cheapest fix is to place a junction box two or three feet away from the box for the fixture, and splice to new 90C NM Cable from the new junction box to the fixture box.

The boxes would have to be accessible from the attic, and the work would have to comply with all local and national electrical codes.

nikomc0;
The basic phyisc's are that heat rises here, and tends to create wires that are brittle from exposure. This is why there is usually insulation bettween the element and junction box.
A fixture displaced from the original junction, such as chain hung, would get you away from this problem.