You'll have to get out there, hit the phones, burn some shoe leather, and build some real world relationships to get people using a brand new platform with no other reference customers.
Rather than think of them as customers, why not approach your earliest ones as partners who will help you test, refine and improve the product. The best partner will be a passionate early adopter who is really keen on your solution to the extent that they will put up with it's current shortcomings, put the effort into making it better, then act as a reference and evangelist.
Also, a wise man (bear?) made the point to me yesterday that there is no point in building a product and all that surrounds it until you've managed to excite people about the idea. If you talked with people, found out their exact pain point, and worked out exactly what excites them, your earliest customers are there for the taking.