I have a couple of ideas on how to achieve what you want.
I believe the Mini-Tek has a 3.5mm stereo phone jack. You should be able to combine these two items.
Item 1:3.5mm Mono Plug to 3.5mm Stereo Jack Adapter
Item 2:3.5mm Stereo Plug to 3.5mm Mono Jack Adapter
Plug Item 1 into 2. Plug your cable in 1 & plug 2 into the Mini-Tek.
EDIT: You might not need the second item, but I forget which side would have the sound if you just use Item 1.
The site I linked to has very good prices. Perhaps you can find other items to make up a minimum order or can use the information pages to find something similar locally.