You can install concrete driveway pavers over existing asphalt, although it is not recommended. Asphalt is more subject to freeze/thaw damage, heaving and cracking with extremes of temperature. It is therefore less stable than some other paver bases and may cause the concrete pavers to shift and crack. Some paver manufacturers will not give a warranty on pavers installed over asphalt in areas with temperature extremes. There are times, however, when installing pavers over asphalt is better than removing the old asphalt driveway and starting over. The technique is similar to installing pavers on earth.
Make sure the asphalt is in good condition. Repair any cracks, chips, holes, ruts or other damage with an asphalt patch material. Keep the surface as smooth as possible. Put some sort of edging, preferably metal or heavy plastic, at the edges. Sink it to just slightly below what will be the top of the finished pavers.
Spread landscape filter fabric over the asphalt. This will be a sealer to keep the sand bed for pavers intact, while allowing some drainage. Then put a layer of coarse sand over the fabric, at least a 1/2-inch deep. Smooth and level it, using a board. Then compact the sand with a hand tamper or a rented mechanical one for larger areas.
Lay the pavers in any pattern you desire. Put them as close together as you can — use a wet saw to cut any to fit if necessary. Once all pavers are set firmly, spread sand over the top and sweep it into the joints between pavers. Use a fine or polymeric sand so it will fill small crevices. It may take several tries to get sand in solidly between all pavers to stabilize them.