Yes, you can use them in only one location on each arm, but it will limit the total amount of adjustment you get out of them compared to using a full set. Whether or not this is enough, I can't say. Depends on the alignment your after. If you want another set, you can get them from Rock Auto for under $30 for a pair within a few days.
FYI, getting camber is usually not the issue. Getting enough postive caster usually is the issue. This will require you install them the opposite of the instructions in the box. But agian, it depends on what alignmnet specs you want to put under the car.