If the computer has a free ISA slot, the recommended solution is to use a MIDI/SMPTE interface card such as the Opcode/Musicquest MQX-32M, which supports 2 MIDI channels and SMPTE code directly. This gives the fastest frame updates and does not drop every other frame. More information about the card is available at http://www.opcode.com/products/winhardware/mqx32m.html.
Another option, if the PC has a Sound Blaster compatible sound card that can read MTC (MIDI time code), is to purchase a SMPTE to MTC converter such as the JL Cooper PPS-2 Synchronizer (not available from Martin Professional) and a cable to split the DB 15 connector on the sound card to MIDI In and MIDI Out. Information about the PPS-2 is available on the Internet at http://www.soundtech.co.uk/jlcooper/stjlcpps.htm.
Once the hardware is installed and configured, select synchronisation 2 from the Control Panel. To synchronize empty cues, click on the left panel of the status bar that shows the time code while the time code is running. The cues can be edited later to include the desired effects by calling the cues on stage, modifying them, and then pressing "Record" -> "OK".