There's "tungsten putty" or "SuspendStrips" (lead tape).

I had the "putty" stuff a long time ago & it worked OK .... just a bit messy to deal with. I had the SuspendStrips in the "dot" shape (called SuspendDots), and used them on jerkbaits to make them suspend deeper. They come in rectangular shapes, too. Neither one would compromise the integrity of your line, like crimping a lead split shot on will.

If I were using the putty stuff, I'd form it like a trolling sinker (torpedo shape), so it'd show up "big" on the Livescope. If I were using the SuspendStrips, I'd roll them around the line to make them show up, rather than flagging them on the line ... which would make them pretty much disappear on the screen.

(*Disclaimer)
SuspendStrips or SuspendDots only weigh 0.01oz each .... so you'd have to use more than just a few to add much weight.