What you can do is create some simple MEL scripts to modify an object's translate attributes, and then bind hotkeys to trigger those scripts. You'd have to get the name of the selected object, get its position, and then change that depending on which key you press. Some MEL commands that you might need:
Code:
ls -sl; //gets the name of selected objects
objectname.translateX //an object's X position attribute
getAttr objectname.translateX; //gets the object's X position
float $foo = `getAttr objectname.translateX`; //assigns the object's X position to a float variable named $foo
setAttr objectname.translateX 5; //set an object's X position to 5
If you look up the MEL commands in the help docs, it shouldn't take you too long to create the commands that you need.