Most timing software uses particular pins on the parallel port to read the sensors from. These pins are 10, 11, 12, 13 and 15 and they are on the so-called BASE+1 address (= parallel port addres + 1). With this setup, you can read 5 sensors on 1 parallel port.

Timing more than 5 lanes, the "easy" way
This is to install a second parallel port in your PC. You can get an ISA parallel port card cheap and getting it to work is a relatively simple task most of the time. You can just connect the 4 or 5 additional lanes to the same connectors as the first one, but now on the second port with a different address.
If all hardware works, SRM will show 2 parallel ports when setting up your lane addresses.