I've travelled from Nth Co. Dublin to Sandyford Ind est in about an hour and five these days, but thats leaving the house at 9am. Other I leave at 6am. I rarely drive during winter but the completed M50 might change that.
To answer your question, its not possible to travel your commute without using the M50. But this is a good thing as the new widened M50 is actually the best way anyway, and its really a case of how much of the M50 you wish to use.
In other words, from Dunboyne, do you join at the M4 or Redcow junctions. I'd pick the M4; the quicker you get on to the widened M50 the better; from there on its non stop to Sandyford.
However, depending on what time you need to be in Sandyford, getting into the Ind Est (if thats where you are headed) can be very tough.
Also remember that getting to work in your case will always take less than getting home. In the evening its even worse, and can take 15-20min just to get from Sandyford out to the M50 from 5-6pm. Then you have a massive toll-bridge queue in my case, but I assume you can take the M4 again.