Sounds a good idea... you might need to cannibalise a headset, or just find out the connector type. Shove it in the empeg's aux-in and you should be sorted.

However, note that these systems often use the headset wire as an FM aerial (which is one of the reasons you can't use the radio without a headset), so if you're going to do this, the signal might vary - but most importantly, try and make the cable run from the mobile to the empeg approximately the same length as the original headset wire.

Let us know how you get on!

Cheers,

A.