Here's the method.
http://www.ipdusa.com/pdf/PI-297TempBypassKit.pdf
It gives sufficient detail even if you've never done any fixit projects on your car.

The link shows the cure using a custom-fabricated jumper wire.
There are variatons possible of course.

Soldering in a wire works well, if you can solder.

My own preference is to use 2.5 inches of 16-gauge wire with butt-cut ends. No stripping of insulation. Drive a thin probe up each end of the wire to make a hollow. Use needle-nose pliers to push the hollowed wire end onto the appropriate pins. Reassembling the cluster holds the wire in place. Proven in over 75,000 miles and 18 months in the longest-running of the three cars I've done this on.

18-gauge wire is certainly enough to carry the current. However 16 gauge household extension cord or lamp cord wire is thick enough - and the insulation is stretchy enough - to slip over the contact pins and get good contact.
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Sven: '89 245, IPD sways, electric rad. fan conversion, e-codes, 28+ mpg - auto tranny. 850 mi/week commute. '89 245 #2 (wifemobile). '90 244 (spare, runs).