PS90 is designed to run on the chamber pressure of the 5.7X28 round witch is about 50,000 psi, the 22 WMR has a pressure rating of 24,000 psi, so a simple modification of chamber and feed system is not going to work. rumors of 22 WMR conversion kit have been floating around since the '90's but no one have been able to make it work with such low pressure.
For future reference it is illegal in Canada to export firearm and firearm technology to China, US's ITAR regulation also made every Canada firearm business sign an end user statement regards to resales of arms to a third country, which is the most important first step in the reverse engineering process.
US firearm importation ban covers all non-sporting rifles not just red rifles, US market is not a option at all.
If if really want PS90 in 22, you are better off talking to to Walther or GSG of Germany than Norinco.