1) Connect your computer to the audio source using Line In on your sound card.

2) Check you computer's sound recording settings to make sure Line In is active. If a Line In entry is not present, right-click in the listing and make sure "Show Disabled Devices" is checked, then right-click on the Line In entry and enable it, and set it as the default device. Disable your microphone so that there will not be any interference.

3) Play some music through the Line In and make sure the bar graph moves, indicating that sound is being received over Line In. 

4) Launch Replay Radio 9 (RR9). Open up the Settings. In the Audio->Capture tab, make sure there is an entry for "soundrecorder.exe". If soundrecorder.exe is not listed, add it via the Add button. Click OK to save settings. 

5) From the Windows Start menu, launch Sound Recorder. Just start typing soundrecorder.exe, and the search feature should find it.

6) Play some audio through the Line In. Verify that Sound Recorder is picking up audio. In RR9, click the Quick Record button. Verify that RR9 is recording audio. Click the Quick Record button again to stop recording. 

7) To setup a scheduled recording, click the Add Show button. Here are example settings:
Name: Line-In test 
URL: http:// 
Capture: Record Audio Output 
Launch: In External Player (choose this or In Browser) 
The rest of the settings are up to you. For a test, choose a start time 2 minutes ahead of the present, and have the duration just be 2 minutes. 
Click OK to save the schedule.

If all goes well, at the set time RR9 will begin recording from Line In. Technically, RR9 will begin recording from Sound Recorder. Sound Recorder needs to be open for recording to actually happen, and anything that Sound Recorder picks up will be mixed into the recording (which is why it is recommended to turn off microphones). RR9 is meant to record from streaming web services, so by putting "http://" into the URL field, we open a blank browser window, and RR9 will record from whatever is active, that being Sound Recorder.

Sound Recorder does not specifically need to be running. I used it as an example. However, a secondary program needs to be actively running (prior to the schedule time) which has the ability to playback a Line In feed, and that program needs to be in the Capture list. Many laptops do not have a Line In, although the above method should work with a Microphone jack as well (just don't disable the microphone in that case).