I think the answer will depend on how far you wish to go, how much money you're willing to spend, and whether or not you believe much of the debate that states the new OSHA levels are not low enough.
Keep in mind that it is not necessary to develope engineering resolutions to exposure limits above the PEL.
Work practice methods can be implimented which may be more economical than engineering practices, and maybe enough to comply with the new standard. But if its not, then engineering methods would be mandatory.
Much has been written about whether or not the new level is low enough, and many advocacy groups are angry over the established level, saying that its not low enough. I would argue that maybe even their level may not be low enough. I'm just not sure there is enough evidence out there to justify their chosen level either. It may be that they chose their level arbitrarily as well so as not to anger industry too much. Its not like the advocacy groups are free of politics and sincere in looking out for our benefit. Many of them are as suspect in their motivations as they accuse industry and OSHA of being.
Bottom line is it will be up to you as to how far you wish to take it, based upon economics, and evaluation of the current data, and conscience.

To add just a little to Jeff's answer, you can go to the OSHA website and read the minimum requirements set forth by OSHA. Like Jeff said, the sky is the limit as far as what extent you want to take it.