Before I had anything installed on sysnand:
1- I installed BBM with FBI on sysnand (Boot miniPasta from 2.5 HBL, then boot FBI from HBL, install BBM cia to sysnand)
2- Once BBM is installed on sysnand, you can install anything else on sysnand, as long as you boot miniPasta first.
3- So, boot into Pastamode (ie, miniPasta), then install DevMenu cia with BBM on the sysnand.
4- Now, once you have DevMenu, you can install any system cia on the nand, even overwrite them.
It's that easy
Now, as for the version of those two titles, it's up to you to make sure you have the correct ones.
I can't link to them in here.
Good luck
Edit: Make sure you install DevMenu_v0.15.8(r37904). It's older than BBM.
Look at this tut:
http://www.maxconsole.com/maxcon_fo...rade-N3DS-MSET-*proper-way*?highlight=devmenu
Q: I can't install MSET CIA and receive error on trying
A: Do not use DEVMENU 6.2 or BBM, use the old DEVMENU.3DS!
(It should display '0.15.8(r37904)' on top when started)
Now, disregard the fact that he's using a GW and devmenu.3ds.
Use whatever you have, but devmenu.cia with FBI (after booting in pastamode, remember) also works