Only time for quick answer. Ask if confusing.
For me, easiest is appending a few commands to the end of the games .map file
http://www.dom3minions.com/docs/map_qref.txt
If someone elses map, dupe to new name. It will use the same image file so not much work involved.
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per peer-pressure preoccupation
My maps, mods, and mullings can be found at
http://www.Dom3Minions.com