I am defining a monk as a character who uses magical attacks and defenses in close combat. This basically means that we can create a monk-like character by simply restricting which spells he or she is allowed to learn. The restriction, then, is simply that the monk-like character cannot cast any spell with a range of greater than 5 meters.
There are some odd bits about certain skills that fit within this restriction, but don't seem like they would. For example, breath-like weapons have a length, not a range