Fallguy,
I use 601/105 combo.
DG601 is just a bonding agent for DG sealants like 105/101/111. It will improve the longevity of those sealants. Like Mike said, DG601 doesn't correct swirls and i just usually use applicator foam pads by hand.
To apply DG601, use applicators (or if you use a PC a finishing, non cutting pad). Spread it thinly, allow to haze BUT DO NOT WIPE OFF YET. Then apply your sealant like the 105, wait till it dries up a bit then buff off with MF towel.