Your answer lies here
It's actually a bug, but a useful one:http://www.arturia.com/evolution/smf/index.php?topic=12829.0
First you need to use the MiniBrute Connection Software (via USB) to turn on the "ARP Hold mode" - which I guess you already have if you are doing sequences already.
Then put Arp switch to Hold
Hold down a key (like you would to start entering notes)
While still holding down key, flip Arp switch to OFF.
While still holding key, flip Arp switch back to Hold.
Let go of key
Begin bunching in notes for your sequence. No need to hold any notes down, just pop them in the order you want, and it can be less than 16 steps... can do 3 steps, 5, 8, whatever.. up to 16, with the benefit of being able to do repeats of the first note (i.e. C, C, D, E)