There will be not Linux version. Why?
I didn't see the source, but mIRC is probably using Windows API calls directly. If Khaled used a library that made it so that mIRC would have been portable, mIRC would already been ported (whould have been made with very few changes).
Porting mIRC means re-writting it all from scratch.
There are alternatives on other operationg systems. If you are not happy, you could write your own portable IRC client
What? You won't switch from Windows to Linux just because you don't have mIRC on Linux? Tell me, why do you want to switch to Linux then??