As far as I know, mIRC should be able to use any of the OpenSSL libraries that are out there, newer or older. The usual reason why mIRC won't load an OpenSSL library is that the library itself uses external DLLs that are not available on the user's system. The required DLLs vary depending on the compiler version with which they were compiled.
I took a look at the dependencies for these particular OpenSSL files and they require MSVCR90.DLL. My system does not have that DLL which means that I also can't use them without downloading that file first. When I download and install MSVCR90.DLL, the dependency checker (independent of mIRC) that I'm using reports another missing DLL although it can't seem to find out what it is.
I would recommend contacting the organization that is providing these particular OpenSSL libraries to ask for help.
Update: I have been unable to load this DLL into mIRC on either Vista or XP. It fails at the very first step of loading the library, which probably means that the issue is due to an external dependency, such as a missing DLL.
Last edited by Khaled; 02/07/08 01:26 PM.