I believe any S2000 theme will do progressive (that's why the top prize is always a sticker, so it can be replaced by progressive).
Not hard to do progressive, you just need a key chip and a meter. Easiest meter to do is the spectrum meter, supported natively within IGT software, all you need is the meter, the machine controls everything. The meter is usually mounted on a bracket inside the top box and aligned with the large window on the special progressive glasses. Some of us made custom enclosures to put the meter below the topper, and outside the topbox as some of these special progressive window glasses can be hard to find. The other external solution is mikohn and it involves the use of an external controller. The machine in this case does not handle the progressive and only sends coin in and progressive hit data to the controller. Used mostly in banks of machine that share a progressive.