I would say acquiring Scott Linebrink is a nice step in that direction.
But now it turns out that Damaso Marte is also available. Marte, you may know, is a lefty, and he's good. He's been well above average his entire career, and is having a great season so far this year. His splits are ri-freaking-diculous: in 50+ PAs against lefties this year, he's allowed a .085/.189/.085 line. He's credible against righties as well.
Dave Littlefield has been known to put a high price on his middle relievers; then again, he's been known to like fringey power outfielders. Maybe Gabe Gross and a C+ prospect for Marte? I think I'd do that deal. Imagine the resulting pen: