I used a 6-ft Hawkline hog with my Mahindra 5525 to mow my 10-acre ranch. Got tired of laying on my back under the mower with an angle grinder (yes, I had the mower safely blocked). So one afternoon I took that angle grinder and cut a hatch into the top cover of the hog. Welded some angle to the parts to attach the hatch to the hog. Used two steel stakes to hold the blade steady while I ground a new edge onto the blades.
<img src="http://www.tractorbynet.com/forums/files/owning-operating/446460-brush-hog-blade-sharpening-img_3780-medium-jpg"/><img src="http://www.tractorbynet.com/forums/files/owning-operating/446461-brush-hog-blade-sharpening-img_3781-medium-jpg"/>
Since I only used the hog to mow weeds on my hayfield, I sharpened the blades to a edge that you would use on a riding mower. Mowed with the rear of the hog 2-3 inches higher than the front to get a nearly lawnmower finish. Every so often I'd hit a rock or something and have to re-sharpen the blades. About a 15 minute job.
Good luck.