I've compiled the DLL's for the latest OpenSSL version which has been released Sept. 29th. I use those myself in several applications and for some reason they're named differently for FlashFXP. To fix that rename libssl32.dll to ssleay32.dll and copy both the .DLL's to your FlashFXP directory. Once you've done that you're good to go.
You can find the DLL's (and openssl.exe) here:
http://www.xs4all.nl/~caine/openssl-0.9.8d.rar
Enjoy.