Unfornately you will need additional hardware. Your best bet will be to get an MST200 and use it to connect to the MSR2000. You can then wire the RAP-109 to the MST200.
Something like this:
RAP-109 -----Eth0-----MSR2000 -------- 5GHz Mesh -------MST200 ---- Eth0 ----RAP-109
On the MSR2000 you would need either a 5GHz Omni antenna or a directional antenna such as the ANT-5314. The MST200 has, essentially, the ANT-5614 built-in.