Products available from Sparkology:

Matrox G450 VGA card with GL6 Genlock system $US2000 each,
also available for hire at reasonable rates
Read about the Matrox G450

Also available on the Matrox Parhelia Graphics card US$2300 for 3 VGA outputs
Read the installation and notes file for the Parhelia card here http://www.sparkology.com/PD8Readme.htm

Read the installation guide and features of the GL6 genlock system here