retrieving ISO-8859-1 webpage encoding problem

[andddreass]

My targeted webpage is written in ISO-8859-1, which I use hoxy's reverse proxy function to get to.
After injecting some html with cheerio and returning the webpage to the client all special characters such as 'åäö' show up as question marks. I have tried modifying the request and response headers to all combinations of utf-8 and ISO-8859-1, still I get the same results. Is this a known issue or am I just doing something wrong?
webpage tested on: http://www.hemsidan.com/