In order for the OP to get the wheel trued, I suspect he really needs to exert the opposite bending force to the rim so that it's at least flat; spoke-tension can only make up for so much. While it's possible to loosen spokes and bend the rim, I find it easiest to just unlace the wheel completely and use a glass coffee table as a guide to flatness. Find the high/low spots and mark them. Then place the rim on the edge of a door-frame and PUSH!!! Don't over-bend it, but do it incrementally until the rim lays perfectly flat on the glass. Re-lace rim onto wheel and you'll find truing will be A LOT easier.
Now the strength of the wheel will still be weaker than a brand-new rim, but definitely much stronger than it is now. I'm still riding on some of these re-bent wheels 10-years after fixing it this way. Then again, Mavic MA-40s are legendary for their toughness; probably more durable than anything they've produced since.
Oh, and get an electric screwdriver and file a slotted screwdriver bit into the shape of a nipple-driver. You can unlace a wheel in less than 3-minutes and build it back up in 5-10.