hi - i just acquired a 1998 v70R with one volvo brand locking wheel bolt on each wheel. The only problem is I need new tires for it, and I can't seem to find the special piece (key) that fits into the "lock". They left the package and everything next to the spare, but no key...anywhere!! now what?

I used to use (optional Volvo) wheel locks on my '98 v70-t5 until one of them crumbled when trying to remove a wheel. Several tire shops refused to touch the problem, but luckily, I found one with some creative extraction tools and a gorilla of a guy to wrench it off. The alternative would have been Very Expensive. That was during my fifth set of tires on the car (I'm now on my eighth @ 178K miles). There are enough alloy wheels around now for me to not worry about them being stolen. It also helps that I'm not in a high-crime area, just average.
The moral: Locking lug bolts don't last forever, particularly if subjected to impact wrenches (used by most tire shops). The more you diddle with them, the sooner they will fracture. I rotate my wheels (swap fronts to rears) every 5K miles to even out tire wear, so the wheels get unbolted frequently.
Since you have an "R" (lucky you!), you probably have the titanium wheels, which are a bit more expensive, so locks may be preferred, but if you drive a lot, I don't recommend them unless you replace the lock bolts periodically.

They are made by Mcgard. My dealer has 2 sets of master keys. You find a master that fits and either remove the locks and install normal lugs or order replacement keys from the number on the master.

Can you get in touch with the person from whom you bought the car? Maybe they still have it.

If it's anything like the 240's lugnut guards, I think the actual manufacturer is McGard (or something like that) -- and they're a tough nut to crack, so to speak.

A Volvo dealer, though, might have some "master" key -- I'm sure there's been times when a customer forgot to drop off the key when the car was left for some brake or other wheel-related job, and they had to take it off.