Getting the month (monthname function) and year (year function). The day is tricky since it can be a suffix of st, nd, rd or th. But a if or switch statement might work for this.
i.e., monthname(datefield)+ ' ' + totext(day(datefield))+if day(datefield) = 1 then 'st ' else if day(datefield) =2 then 'nd ' else if day(datefield) = 3 the 'rd ' else 'th ' +year(datefield) + ' through ' + (repeat the first part of the formula for the second datefield.