If the ADSL routers are capable of routes via next hops and not just directly connected as well as default routes and you're not using NAT throughout, first ensure that the ADSL router you're trying to access Winbox on the 3.30 Hotspot box through has a route back to that Hotspot router. Then configure the ADSL router to port forward some port to port 8291 on the Hotspot router IP on the 192.168.1.0/24 network. How you do that depends on the manufacturer of the ADSL router - Mikrotik doesn't make those, so that's outside the scope of this forum as it isn't about configuring a Mikrotik RouterOS device. If the ADSL routers can't function in that fashion consider using them in bridged mode and terminating the PPPoE DSL tunnels directly on the RB750. That is a lot more flexible and gets around one layer of NAT.
If you're doing NAT throughout you will have to port forward on the ADSL router, and the RB750. To port forward on RouterOS see the manual:
http://wiki.mikrotik.com/wiki/Manual:IP ... rt_mapping, you're on your own for the ADSL routers as stated above. NAT on all hops would be such an incredibly bad network design you should seriously reconsider resigning everything, though, starting with terminating PPPoE on the RB750, and then removing all NAT on the Hotspot router. NAT should only happen on AS boundaries. NAT breaks things, don't do it more than you absolutely have to.