of course its possible but its a little weird. the ease of an actual implementation seems like it would be determined by signal requirements of the ic's (ttl, differential etc), clock jitter requirements, i cant imaging that the dac on a soundcard is going to give you a very clean square wave, signal purity requirements (ringing - gibbs phenomenon). i dont know, im no EE but im sure a reasonably intelligent person could do it, but youll probably just end up with a really shite clock for a whole lot of work. uhh, just out of curiousity....why?

Count Binoculars