I imagine a sub-field of mathematics could coordinate the required effort. Mathematicians are familiar enough with the technical aspects (namely, use Latex). Once one sub-field is successful I imagine others would follow.

Done there, been that:

Electronic Journal of Combinatorics: http://www.combinatorics.org/

Theory and Application of Categories: http://www.tac.mta.ca/tac/

As has been noted elsewhere, establishing open access journals presents no technical difficulty, especially with systems such as the Public Knowledge Project's Open Journal Systems journal management and publishing system, which has been around for at least 7 years. http://pkp.sfu.ca/?q=ojs

The high price of 60 years of scientific content is at issue. Of course, the establishment of open access journal should be encouraged.