I have a next LAN scheme:
<MyPC 10.220.0.x> --- <WinServ 2008r2 10.220.0.x> --- <Xerox WC 192.168.0.x>
Server has PrintServer role enabled and printer is shared. I want to monitor the printer's state/errors through SNMP but problem is that I haven't acess to printer directly because it is in a different network. I can operate with printer ONLY as a shared i.e. through printserver, so my question is - how I can make SNMP requests to shared printer? Is it possible?
Your network diagram is vague enough that they could all be on the same LAN. If so lucky, then just set a static route to the 192.168 network on "My PC". eg.
route add 192.168.0.0 mask 255.255.0.0 IP-ADDRESS-OF-MY-PC
If you can ping your printer, then you can access it via SNMP, assuming there are no firewalls on the printer disallowing this.