For special ability upgrades, you have it so a computer (or neutral?) player that has the upgrades gives the related unit to the human player. For example, if player 8 had Lockdown researched and player 1 didn't, you give a ghost owned by player 8 to player 1 and player 1 now has Lockdown.
For normal upgrades (and upgrades such as speed or sight distance), you need to research them. You have to just give minerals/gas to the players.