Support for simple customisable probing area

When probing PCB´s I had the problem that i needed auto-leveling for specific areas (it´s almost never the same size), and I thought it would be nice, if I could simply pass the parameters along.
Not much code, but very useful.
Now I use simply G29 L5 R55 F5 B35 P3 to probe a 4x6cm PCB before milling.
I forgot to mention that I don´t know if it makes a difference if I use float or integer. I used int... might be wrong...