Hi,
I dont think you would have a problem doing a count manually, but the problems may lay in :
1) correctly identifying the type of eggs (species of worm) - there are lots for pigs!
2) Having equipment accurate enough to provide accurate results - ie. to give an epg (Eggs Per Gramme) reading you dont count all the eggs in 1 g of material, you count in a tiny fraction and then extrapolate to get the answer.
Getting the results wrong could lead you not to worm if required or worm if not required, and the difference in numbers is small. eg for threadworm a low count is <100epg where a high count is >300epg.
Thanks