The inFAMOUS2 Hero Edition is a spectacular limited edition bundle. Once the downloads were completed, I switched back to my main South African account and I was able to access and use all of the downloadable content without any issues.
In this case, creating a United States based PlayStation Network account allowed me to use the inFAMOUS 2 Hero Edition Super Voucher and download all of the available downloadable content. I was able to access the region locked content by creating another PlayStation Network account from the region the imported game was from. You do so at your own risk and Vamers cannot be held liable for any incurred damage or incompatibility from utilising this procedure. Please note that Vamers does not condone this method of accessing region locked content.
However, as always, there is a loop hole.
It is possible that the downloadable content codes in the United Kingdom version of the game would work with South African PlayStation Network accounts, but I cannot confirm this thought. This effectively turned the included Super Voucher into a gloriously designed sheet for eliciting paper cuts. This means that as gorgeous as this inFAMOUS 2 Hero Edition bundle is, because it originated from the United States, I could not make use of any of the downloadable content with a South African PlayStation Network account.