* Linking the existing transform tool parameters (X, Y, Z positions) to some KB-shortcuts and a variable nudge grid should be possible. It should even be possible to compile a Java script to achieve such a tool.
* My own .js skills are close to infinitesimal, but others may have a working grasp of Java scripting to implement such a function.
* You may consider posting this request in the scripting forum and await the responses of the resident masters of the martial art of Java Scripting.