SLAs are still available in Sales Workbench, but the only way I could find them was as PN 550.2500 in the PARTS CATALOG section at the bottom. And I checked programming, you can still configure them. But they need to be connected to a digital port (one SLA = 2 DID ports) and you just tell the digital card that's what's on the port (dual DID).
In order to get calls to your fax you'll need to add ANALOG VOICE MAIL feature license. Set two SL stationsin a HG, program the HG as a VM hunt group (flag in HG). For each user build a phantom phone X, and use SYS FWD to set immediate fwd to the HG. Now when call arrives DID sends to phantom X, which fwds to HG...when fax finder answers, the 5000 thinks it's a VM and echoes the ext number into it as DID.