It's not something I've used, but my G120 course notes say that SLS does not require encoder feedback on the G120. Requires a CU240E-2 F or a CU250S-2 control unit. Will probably also require start drive advanced, safety advanced and it mentions that each axis requires a licence but unsure which specific licence it means.
The only mention of specific motors is this:
"Encoder-less operation is possible for all asynchronous motors and the synchronous motors 1FU8 (SIEMOSYN)"
I looked up 1FU8 and they're all synchronous motors, so I'd take that to mean any asynchronous motor can be used but only that specific synchronous motor.
Siemens also says that the G130 and G150 have the SLS function.