Edit mimersql-ds.xml and mimersql-xa-ds.xml for your setup.
To setup a datasource for Mimer SQL, copy standardjaws.txt and standardjbosscmp-jdbc.xml to 
<jboss-home>/server/<choosen-configuration>/conf and mimersql-ds.xml to <jboss-home>/server/<choosen-configuration>/deploy. If you want
a XA Datasource, copy mimersql-xa-ds.xml to <jboss-home>/server/<choosen-configuration>/deploy

If you don't want to overwrite standardjaws.xml and standarjbosscmp-jdbc.xml, just copy the <type-mapping-defintion> for Mimer SQL 
in standardjaws.xml and <type-mapping> for Mimer SQL in standardjbosscmp-jdbc.xml.