Well, obviously, Dave Riba would be able to give a better answer to this than I could -- my father-in-law has run both a kosher slaughter and meat packing operation, and a treif sausage factory, so I suspect he could give a REAL answer. Most of what I know is from conversations with him, and occasional reading of other books and stuff.

But, from my barely-educated layman's perspective, I don't see why you couldn't. Landjager is a mix of pork and beef and lard; I don't see why you couldn't do all beef and suet or tallow. I presume that you'd have to make some sorts of adjustments if lard and suet don't work exactly the same way, but I'd guess that they'd work close enough that you could adapt it if you knew what you were doing.

I honestly don't know how similar pork fat and beef fat are. Flipping quickly through Wikipedia suggests that tallow and lard are pretty similar, so I suspect that this could work. I wouldn't know how to do it, though.