You can just do it - old school $20 way. Look at one of Xzin's posts where he posted a cheap USB number pad only keypad. U'll end up only using + and - key and u can put it left of your keyboard and can easily press those 2 keys with a pinky

As far as shielding / wanding - I guess you wont need to wand / extra dot/nuke till he's 58 or else you steal poor warlocks exp -- heh granted you're a wuss like me and plays in a PVE server