I too am having problems getting the SiL3114 Win64 drivers getting to load.
I use(d) a SATA drive on my 2600+ machine, so I knew ahead of time to copy the drivers to a floppy. So I did, but I could never get it to load them - it was too long ago to remember any speicific errors.
So instead of using the SiL3114 I used the nVidia 2port on that was also onboard, and it doesn't require any drivers for winsetup because it appears to Windows as if it were an IDE controller.
Once I got into windows I tried loading the drivers again, it would come up with an error saying "cannot install this hardware" but it would then make the category SCSI and RAID controllers, and Mass Storage Controller would be in there with the yellow exclamation mark. I've tried a bunch of things to try and get it to work, I've reformated a bunch of times(for other reasons) but still none of the times I try to install it does it work, even today I downloaded the latest drivers from Silicon Image and it still doesn't work.
The only driver diff between 32bit and 64bit should be that 64bit requries a new signature, but it acts as if the drivers start to install w/ the 3114, and it shouldn't even do that if it didn't have the signature.
btw, my system is: http://www.khipset.net/personal/64.htm
(too lazy to post it all)