I don't think you can run bitcoin-qt on a raspberry pi.  

I'm sure you run the bitcoin-qt somewhere in your home
like on your desktop or laptop...
so lets say your running bitcoin-qt on your desktop
& your desktop on your home LAN is 192.168.1.6

then go into your bitcoin.conf file
and set
rpcallowip=192.168.1.*
setting this will allow any computer in your LAN to connect to your bitcoin-qt RPC port

I always like to change the rpcport=7533 to something random but that's me

you have to set this Server=1
it tells Bitcoin-QT to accept JSON-RPC commands

and set this to what you want
RPCUSER=bob
RPCPASSWORD=abc123
do pick a good pass!!!


in bfgminer.conf
just point it to your PC IP & Port
"url" : "http://192.168.1.6:7533",
"user" : "bob",
"pass" : "abc123",

and that's it
do keep in mind that solo mining is really only good if you have Th/s
I'm not going to be like some of the dicks on here & say "your a noob, solo mining is dead" etc.. because that's what they did to me last year  
for the most part its kind of dead
if you have like 1Th/s you have better odds of getting a block some day sooner but if you have like 50gh/s then it could be some time before you see anything.

there is a luck factor to solo mining
you could get real lucky & get a block with 50gh/s or you could be w8ing months if not years
that's the game of solo mining its 50 50 you could be unlucky for weeks & that one day comes where you get lucky

in many ways I feel pool mining is fucking dumb but its the way the game is played, for now.