Hi Graham,
I assume that you are using the original Yamaha cable loom from the T2's 'TO SUBWOOFER' outlets to the sub unit. This comprises a cable with an 8 pin connector at each end and a second cable with a mono 1.4" jack plug at one end (the keyboard end) and an RCA phono type plug at the sub unit end.
These carry the signal from the keyboard to the amplifier in the sub unit, and also carry the amplified signals for the left & right satellite speakers back to the keyboard.
The final connection for the speakers is via a mono 1/4" jack socket at each end of the rear of the keyboard. They are marked 'TO LEFT SPEAKER' and 'TO RIGHT SPEAKER'. These form a convenient way of accessing the L and R speaker signals, even if you aren't using the Yamaha original speakers. The original short cables supplied for this connection had a 1/4" mono jack plug at one end and an RCA phono plug at the speaker end. If the speakers that you want to use don't have a single phono input socket, then you will need to make suitable cables for them with 1/4" jack plugs at the keyboard end.
The TRS-MS02 manual suggests that the original satellite speakers were 4 ohm impedance, so if you use alternatives with a higher impedance, you may find that they are not loud enough, but you wont hurt anything by trying them!
Regards
Ian