Running a hundred feet of 4 AWG cable above ground for several days is one thing. Having it lay there for weeks or months is quite another. A tripping hazard. Certain ultraviolet sunlight destruction. And last but not least doing this is a trifle to those who do not have to purchase a lot of # 4 THHN.
Don't know about where you live but in Sonoma county California, such a run of cable aboveground is a pricey code violation. The county fire department inspects and code enforcers have police backup. This is from January 2011, their lips to my ears.
The "way to do it" of course, is to not check, get fined, then do it according to code. Making a telephone call is, after all, exhausting.