The best trick for Pindle, regardless of what character you use is positioning your merc correctly. Sorcs do this easily with Teleport.
Teleport twice from the portal until you are just outside the hall.
Teleport one more time inside the hall (try to get about halfway between Pindle and the hell entrance).
Walk back a couple of steps while your merc walks forward to engage the group.
Depending on your build you do different things here, but using a Cold or Meteorb sorc, fire 2-3 quick Glacial Spikes to freeze some of the group.
(I switch to MF-switch here).
Now pound with your heavy hitter, Bliz, CL, Lightning, Meteor, whatever. Spam with your spam spell Fireball, Blast, whatever. Every sorc build I've played (Bliz, Meteorb, Blizzball, Lightning) can kill Pindle and his crew before the guys outside even wake up all the way.
Depending on how rich you are, give your merc some gear to help him survive.
- Moderate: Vamp Gaze (Um), Up'ed or Eth Shaftstop (Um), Reapers (Eth if possible, add a Shael, IAS jewel, ED jewel, whatever you would like). This gives good ll, 30% DR, max resists, decrep slows and makes monsters -50% physical res. This is a very useful merc setup and I used it for a LONG time on all mercs.
- Rich: Eth Andy's (Ral), Eth Fort, Eth Infinity. This helps a sorc with the -res, the merc has great defense, insane damage, max resists, +skills, +Str, etc. It's pricey but very nice. My sorcs all use this setup on mercs now.
There are even more expensive setups, but if you're that rich you already know what to use.