Even a flatbed scanner from Epson will be a lot better working than a digital camera. Better dynamic range, for about the same price as an adapter thing you need for photographing them with your camera, better ability with negatives, specialized software to get rid of dust and scratches.
And a specialized 35mm slide scanner will do an even better job, with better resolution.
It can be done with your camera, but an ideal solution it is not.
Canon EOS 350D, Tamron SP AF 90mm F/2.8 macro, Sigma 18-50mm F2.8 DC EX, Canon EF 70-200mm f/4 L USM, Tokina AT-X124 Pro 12-24mm F4, Soligor 1.7x C/D4 DG Teleconvertor, Manfrotto 724B tripod, Canon Powershot S30