I can't seem to get widescreen working. I tried doing the HEX hack but it can't find the address's specified in WSGF. I read somewhere that it does work for the GOG and Steam versions.

There is a thread where we talk about hacking the .exe for widescreen, may be you should take a look at it, may be there will be things who will help you.

I remember that I had hard times too for hacking the .exe, because I knew nothing about this things (and still know almost nothing now :P). Use as specified [url=http://www.wsgf.org/dr/rollercoaster-tycoon]here, be sure you search in hex mode and not in text mode (it was a mistake I was doing at the beginning), and don't copy/past the values you're searching : enter them yourself (if I remember well, it was another trouble for me who prevented me the research to work).
(and remember if you look into the thread I indicated that if you use the latest GOG's installer version of the game, the .exe isn't packed anymore)

But I confirm that it works on the GOG version, for the english and french versions.