I've got a switch (TP-Link T1600G-18TS) that is connected to a router (RB951G-2HnD). I want to access it's management interface from a PC connected to the router.
According to it's (switch) manual, to access the GUI you need to connect it directly to a PC, set up the PC to use an IP address 192.168.0.x/24 and then browse to 192.168.0.1. Is it possible to make such a connection from a PC connected to a router instead? If so, how can it be done?

I haven't looked at any detail on that switch's management behaviour.
However, I have modems in my environment providing PPPoA to PPPoE brigde from xDSL. RouterOS then handles PPPoE client.
To view modem stats, I have to connect to the modem on 192.168.2.1

My ether1 interface on RouterOS is set to 192.168.2.100/24
I am then able to telnet from RouterOS to that IP address (because the two are connected directly on that subnet)
In order to access the modem from another subnet (VLAN) known to RouterOS, I need a static route on the modem for the return(reply) path and firewall filter rules in RouterOS to accept the traffic.

Example:
Modem 192.168.2.1/24 has a static route 10.5.0.0/23 via 192.168.2.100
RouterOS: Source: 10.5.0.0/23 Dst: 192.168.2.1 protocol:tcp port:23 action:accept

I do not know if that switch will allow you to set a static route. The easier method, if possible, would be to change the default management address of the switch to match the LAN subnet.

Assuming that your switch is connected to the "inside" of your router (one of the LAN ports), where your PC is also connected (wired or wireless), you should proceed as written in that manual.
So change your PC address from DHCP to 192.168.0.2/24 and access the switch on 192.168.0.1
There, change the IP of the switch to an address in your usual LAN range (e.g. 192.168.88.2).
Then you can set the PC back to DHCP and access the switch on 192.168.88.2.
Make sure the address you choose is not in the DHCP pool range of the router, adjust it if necessary (e.g. to 192.168.88.10-192.168.88.250)

sjoram, pe1chl, thank you for your suggestions! Setting the switch address in my LAN range did the trick!