You can power two accessories from one channel as you say. Aux1 will activate the momentary to common connection, and Aux2 will toggle the on/off connection. These can be independent accessories, noting that they share a common return. Both of these accessories would use the same accessory # in the configuration, and they'd be wired to the same three connection block on the SC-2.
The accessory # are sequential, each of the connection blocks on the SC-2 is numbered separately, however the momentary and on/off connection to a single connection block share the same accessory #.
I'm not familiar with those two particular accessories. As long as one of those accessories requires a momentary contact and the other requires an on/off contact, you have it correct.