If you want a digital patch, you need a 7pin cable such as Pro-Digital or Oade (active or passive), if you want an analog patch, you would run into "line-in" using an 1/8" mini - mini or 1/8" mini to RCA depending on the lead deck/device.
Clarifying from a $$ perspective:
Digital 7 pin: active will cost about $150 with shipping, passive a little less, but I haven't priced it. You can try to pick up a used one, but they're few, far between, not always dependable.
1/8" mini - mini or 1/8" mini to RCA depending on the lead deck/device: will cost less than $12 from Radio Shack for both.
I use all three as needed. I always try to use the digital 7pin for obvious reasons (better signal in and out). But if someone can't give me a digi out, then I'll go with either of the 1/8 inch cables.
I recommend you start with the low cost alternative, meet some tapers and talk to them about the benefits of 7pin digi vs. 1/8" analog.
+T for the find and the battery work, man!!