How can I install .deb files for Cydia manually (without wifi)?
You can add .deb files and install apps from apptrackr, etc.. using the app iFunbox. I actually just used it the other day to locally upload my custom sms-tone pack. So download your needed .deb files from online, then transfer and install them via the program iFunbox.

http://www.i-funbox.com/