Well, if you notice not many recipes are all sorghum around here, but most people use other fermentables cover/compliment the taste of sorghum.
That being said here are some general guidelines people around here use when using sorghum:
1. Add it at flameout or just before. The longer it boils the more metallic twang you will get.
2. Keep the sorghum syrup to 2/3 of your grist or less. A nice hop profile, 2/3's sorghum and the rest rice syrup, rice syrup solids, honey candi syrup, etc. (or some combination thereof) and you'll have a good beer.
3. Some people claim using yeast nutrient with DAP reduces the twang too.