Look at the KF5INZ EASY DIGI thread in the Ham Made Gear forum
Originally Posted by W7EMI
In my early days of Soundcard digital, I made interfaces that went to DIN plugs in the back of my Icoms and fit in an old film canister. You can certainly go through the front end Mic connector of your Alinco (My packet radio is an Alinco and my 1200 baud cable uses the mic plug and external speaker jack). the cost of the parts is pretty cheap, even with isolation and it's a nice little project to work on. I think the most expensive parts I had to buy were the stereo cables.
This interface, along with a free program, will give you a good start into digital. That being said the commercial interfaces make life a lot simpler. I have an Icom NoMic for mine now.