I've attempted to fix the amd64 warnings in Makensisw.
I have compiled this successfully with no warnings on both windows (64bit) and linux (32 bit).
I've marked unavoidable typecasts with BUGBUG64, there's six of them.
The code just needs to be verified by another pair of eyes, see attachment.
Update, I've managed to remove two of the typecasts by rewriting two of the functions a different way.
Also, I might be able to remove one more, I'll do some more testing.
I've attached the updated file below.