If you are really interested in learning more about this style I highly recommend Eric Warner's Style Guide Series book "Kolsch". By far the best printed resource for brewing these beers.
+1 on the Warner book. It's quite good.
Despite what the BJCP Guidelines say, Warner suggests that authentic Koelsch has a fair bit of wheat malt in it. Conversely, American style Koelsch uses just Pils malt. His recipe for a German-style Koelsch is as follows:
7 lb. Pils Malt
0.75 lb. Wheat malt
0.44 g AA from Perle (when boil begins)
0.29 g AA from Perle (40 minutes in)
0.2 g AA from Hersbrucker (at knockout)
117 degrees F mash-in
heat at 2 degrees F/minute to
143 F rest for 30 minutes
159 F rest for 10-15 minutes
heat to mash out temp.
Vorlauf 10 minutes
Oddly enough, Warner suggests mashing-out and sparging at ~170-173 F, which might promote tannin extraction.