Using a C+C pm-129a to measure current

I am new to the site, hello everyone. So i just bought two pm-129a meters to monitor a 12v battery system. The applications listed include voltmeter and ammeter but the data sheet included only show voltmeter applications. How do I monitor a dc current level with this? Here's my max current level also, which is throwing monkey wrenches at me left and right... up to 100A @11-14vdc. So with meter sensitivity 0-200mV, I basically need to drop 0.001v for every amp flowing putting me around 1mOhm for a shunt. Do they make resists that low? I know using a diff opamp measuring voltage drop across a shunt resistor is the basic idea but the size of resistor for 200A has to handle 40w(?). Wow. So since I'll never exceed 100A, I can scale down to 10w but where do you get a 10w 1mOhm resistor? There's got to be a better way to do this, and please don't say analog meter. Any help would be appreciated! Thanks in advance.

Panel meter info: ".web-tronics.com/led9vingrpam.html" it's just w-w-w in the front, i'm not yet allowed to paste links yet.

They do indeed make 1mΩ, 10W resistors for the very purpose of measuring current. They're called current shunts. Current shunts are commonly made with a 50mV or 100mV drop, and 100mV types are available in 100A versions.

For example, a Google search found http://store.altenergystore.com/Meters-Communications-Site-Analysis/Shunts/100A-100Mv-Shunt/p4637/ and http://www.galco.com/scripts/cgiip.exe/wa/wcat/itemdtl.htm?pnum=FN-100-100-CMI among others. Those will give you 1mV per amp for a direct ampere readout on your meter.