installing xm radio in 03 accord

where is the fm antenna? that is all I need to know to complete the installation

What type of xm radio are you installing? OEM or Aftermarket?

Rear window.

and it should plug into the back of the radio...that would be the easier place to tap into it.

Well I bought it at circuit city, it's called the XM Sportscaster
It came with the sureconnect. It says to connect it to the FM antenna
http://www.satellitesounds.com/images/backend/informationpages/manuals/sureconnect_manual.pdf?phpMyAdmin=beBm%2CK8v7vObOa3KUtRZFwkJ6z8

Don't use that wireless crap!!!!!  Buy an in-line WIRED modulator and plug it into the back of the radio, then plug the stock antenna to it.  Otherwise you will never get the quality of sound that satelite radio is known for ..... I tried the wireless modulator first and found that I could never get rid of the static no matter what frequency I tried.

http://store.xmfanstore.com/fmdirect.html

Well I wouldn't call this wireless...the modulator connects to the fm antenna then I run a wire underneath everything up to the XM radio and connect the antenna into the coupler that runs from the fm antenna.
 
How hard would it be for me to install that inline modulator?