Here's what you do:
On the PC that eJ is installed on, install a bluetooth adapter (preferably one compatible with XP SP2):
Go to Control Panel Networks (or whatever) to access the Bluetooth Devics panel and pair your S700i with your PC.
From the Phone, Access the main menu and choose Connectivity:>Bluetooth and you'll notice a Remote Control option has appeared (factory included software). If this is greyed-out, close down any other Bluetooth applications (may also not work if using anything other than the MS XP SP2 Bluetooth stack).
From here, select MediaPlayer that appears on the phone menu.
Now, straight off the Play/Pause option works, but you'll have to program in the other options as follows:
From Winamp 5 (sorry v2 fans), select Options:>Preferences and under General Preferences select Global Hotkeys.

Program the following keys:
Playback: Next in play list CTRL + F
Playback: Stop CTRL + S
Playback: Rewind CTRL + Shift + B
Playback: Forward CTRL + F
...etc, I'm sure you can work the rest out.

Now, you may or may not have noticed that if you move the phone cursor buttons, it moves the mouse around the eJ screen allowing you to select the tracks you desire.
How cool is that?
May also work with a K700i Sony Ericsson phone as well, not tried, but I've noticed this software for this phone on the Sony E site