Not usually. Some older import vehicles (like Volkswagen Beetles) recommended periodic lube changes for their gearboxes, but no modern car or light truck requires it. The reason why is because the oil stays relatively clean and runs fairly cool. Unlike the fluid in an automatic transmission that is being constantly churned (which generates heat) and contaminated by particles worn off the clutch plates, the fluid in a manual transmission or transaxle has life pretty easy. So it usually lasts the life of the transmission.
The only reason you might have for changing it would be if you were experiencing hard shifting problems during cold weather. Most older rear-wheel drive transmissions use a heavy gear oil like 75W, 80W or 90W, which can get pretty stiff at subzero temperatures. Changing to a lighter oil may improve shifting.
Most manual transaxles in front-wheel drive cars today use Dexron II automatic transmission fluid (ATF) to keep the gears lubed. ATF works well because it stays much more fluid at low temperatures. But ATF should not be substituted for gear oil. Always use the type of lubricant specified by the vehicle manufacturer.
The only time you should have to add oil to a manual transmission or transaxle is if the tranny is leaking oil. If you see any grease or wetness around the tailshaft or driveshaft seals, the oil level in the transmission or transaxle should be checked because it may be low. WARNING: Allowing the transmission or transaxle to run too low on lubricant can ruin it.