I own a MiniBrute 2s and you can patch it to external modules easily using the patchbay indeed. Both VCO1 and VCO2 have outputs you could send to your reverb module. You can return it back using the master or ext inputs, master will mix your input to the final audio signal from the MiniBrute, the ext input will send your signal through the MiniBrute's filter, envelopes, brute factor and everything else, this can be controlled with the ext fader in the VCO1 section.
The MiniBrute's manual is pretty easy to follow and there's a full section on the patchbay, you may want to check it out.
I would suggest using the "AMP OUT" rather than directly from the VCOs. I don't think you'll want to apply reverb then your filter. The amp-out is going to be at or near the end of the signal chain.
Page 64 of the manual describes the Ext Inputs. It's not very clear, but I think the Ext In Master jack disconnects the synth when a patch cable is present. I would definitely test that. If true, you could create an insert by going from the amp out, to your reverb, and then to the ext in-master. Just not that your signal will return in mono since there's only one input.