Use a dremmel tool with a fine grit round bit to gently trim nails.
Press the bit gently against the nail and let the tool do the work.
If their nails are REALLY long, start by taking off 1/16th inch 'sections' and gently work back to where you think the quick (blood vessel) should be. If you nick the end of the quick, it'll bleed like the dickens, but it's not fatal. Use syptic powder (sold in pet stores for dog groomers) or cornstarch or flour from your kitchen if you don't have the powder. The powder just helps the blood to clot and form a quick scab to stop the bleeding.
If all else fails - trim a section off each nail working back and forth until you've gone several go-arounds on each nail on the foot. They will be uniformly short that way (this is what I do for our turtles - their nails might be long, but they're uniformly shaped making walking easier).
As for long-term....why not put a few concrete bricks (i.e. paving stones) in their run - like right below their ramp - to help wear down their nails? Helps with mine. And boy, do they like it when I come to flip the bricks up and reveal all sorts of yummy bugs!
