Next you must transfer the file over USB cable from the PC to the iphone using DiskAid or something similar.
The next task is to let Cydia know about this new package.
I recommend this way to do
i.e. to create a folder /private/var/root/Media/Cydia/AutoInstall/ and drop the .deb file there.
instead of installing that software, a more portable way is to fetch a copy of iphone_tunnel:
start ssh on iphone, run iphone_tunnel 22 22 and ssh with winscp to localhost port 22
This can be portable too! All you actually need are winscp and iTunnel folders. First you run Launcher.exe in iTunnel, then winscp.exe. And of course, a batch file is a neat idea.
In order to make it work under OS3.0 you need to use iTunes 8.2 and replace iTunesMobileDevice.dll in directory where itunnel.exe is located with the new one from C:\Program Files\Common Files\Apple\Mobile Device Support\bin.
Itunnel could not work in my 64 bit win7, I find ispirit to replace now O:)