As was mentioned, you can use servo extensions of almost any length. Of course the longer the wire, the more resistance you'll have.

Rodney's advice to solder longer leads directly to the servos is a good one, especially for extensions over about 12 inches max. With extensions you also add connectors, and connectors are another source of resistance. For extensions of 12 inches and under I wouldn't worry about it. (You should consider a larger battery pack that the original though.)
Dennis-