The NCID client software is what actually shows incoming Caller ID on the screen. For the S3 Tivo at the moment you pretty much need to use Tivo's included text2osd utility.
You don't need the ncidd server running on the same machine to use the client. If you have multiple Tivos (or even PCs) you can use the "main CID server" to Collect caller ID info and run just the client software on each.
Once you've unpacked the ncid-0.67-series2-tivo.tgz package into /var/hack you need to copy over Hichhiker's uni2osd script into /var/hack/bin. I had a problem when unpacking the script (from the zip file) with line-endings, so you should run dos2unix on it to make sure it strips any extraneous carriage-returns.
Unfortunately, out2osd doesn't yet work on the S3 with v8 software. Move the original out2osd program to a new name (such as 'original_out2osd') and make a symlink from out2osd to uni2osd.
(dos2unix is part of AlphaWolf's All-in-One Utilities.)
Edit the uni2osd so that OUTPUT is forced to text2osd
My_S3_Tivo# cd /var/hack/bin
My_S3_Tivo# dos2unix uni2osd
My_S3_Tivo# chmod a+x uni2osd
My_S3_Tivo# mv out2osd original_out2osd
My_S3_Tivo# ln -s uni2osd out2osd
Also be sure to add the directory/var/hack/bin to your PATH statement in your /etc/rc.d/rc.sysinit.author file, or the tivoncid client seems to fail after awhile.
### OUTPUT which software to use as output program
Now run the tivoncid client and enjoy Caller-ID info on your TV screen.
Check the /var/log files for troubleshooting, and edit friends and family phone numbers in the /var/hack/etc/ncid/ncidd.alias file. There are lots of good instructions and information in /var/hack/doc/ncid.
My_S3_Tivo# /var/hack/bin/tivocid &
You can also set up just this client on other Tivos and to get Caller-ID.
My_Other_Tivo# /var/hack/bin/tivocid <ip.of.server.address> &