Here is the process I have done to get the furthest I can..

$ is the rapresentation of the shell in a terminal, the command is what I have to write to replicate the situation
# is the error rapresentation
@ is the specific account string

1) Create FreeBSD 9.3 Jail in FreeNAS using default values
2) $ portsnap fetch extract
3) $ pkg update
4) $ cd /usr/ports/net/boinc-client
5) $ ee Makefile
6) $ Change line (adding LINUX) "OPTIONS_DEFAULT= CLIENT MANAGER X11 LINUX USER"
7) $ pkg upgrade
8) $ make BATCH=yes install clean
#1 Error, linux_base-c6-6.6_6 linuxulator is not (kld)loaded
9) $ cd /usr/local/bin
10) $ boinc &
#2 No start
11) Now you need to add your project and hope it runs using the boinccmd CLI... pray about...
12) $ pkg-static install -f pkg
13) $ pkg2ng
14) $ pkg-static upgrade -f
15) $ cd /usr/ports/net/boinc-client
16) $ pkg install linux_base-c6
17) $ make BATCH=yes install clean
18) $ cd /usr/local/bin
19) $ boinc &
#WORK!
#OK #1 & #2 Error solved
20) $ cd /usr/ports/astro/boinc-setiathome-enhanced
21) $ make install clean
Pico & Nano to edit file /etc/make.conf and other in future, because I hate VIM.
If you use VIM ignore steps until 30 and use VIM instead of pico or nano
22) $ portsnap fetch update
23) $ portsnap fetch extract update
24) $ cd /usr/ports/editors/nano
25) $ make install clean
26) $ ln -s /usr/local/bin/nano /usr/bin/nano
27) $ ln -s /usr/local/bin/nano /usr/bin/pico
28) $ pico
#WORK!!
28a) ctrl x
29) $ cd ~/
30) $ nano .cshrc
# change default SETENV editor to nano instead of ee or vi
31) $ nano /etc/make.conf
31a) BOINC_HOME=/var/db/boinc
enter
31b) BOINC_USER=boinc
enter
31c) BOINC_GROUP=nobody
enter
31d) ctrl x
enter
31e) y
enter
enter
32) $ nano /etc/rc.conf
32a) boinc_enable="YES"
enter
32b) boinc_client_enable="YES"
enter
32c) jail_sysvipc_allow="YES"
enter
32d) boinc_client_flags="-allow_remote_gui_rpc"
enter
32e) boinc_flags="-allow_remote_gui_rpc -redirectio"
enter
32f) ctrl x
32g) y
enter
enter
33) $ cd /var/db/boinc/ && /usr/local/etc/rc.d/boinc* start
#3 --> 'idprio: RTP_SET: Operation not permitted'
34) $ /usr/local/etc/rc.d/boinc* onestart
#3 same error, demonstrate that is independent from configurations? I don't know but I'm praying...
Continuing with the setting of my account manually
35) $ pico /var/db/boinc/account_setiathome.berkeley.edu.xml
paste into the new file the 4 line down
<account>
<master_url>http://setiathome.berkeley.edu/</master_url>
<authenticator>@Your_Auth_Code_ID</authenticator>
</account>
ctrl x
y
enter
36) $ boinc_client -attach_project http://setiathome.berkeley.edu @Your_Auth_Code_ID
is needed some "infrastructure parts"
37) $ cd projects/setiathome.berkeley.edu
38) $ ln -s /usr/local/lib/boinc/setiathome
39) $ ln -s /var/db/boinc/projects/setiathome.berkeley.edu/app_info.xml
40) $ cat /etc/master.passwd
Only a dubt about the home directory of boinc... but is correct
41) $ cd /usr/ports/astro/boinc-setiathome-v7/
42) $ make install
43) $ cd /var/db/boinc
44) $ boinccmd --project_attach setiathome.berkeley.edu @Your_Auth_Code_ID
#4 --> 'can't connect to local host'
45) $ boinc -attach_project setiathome.berkeley.edu @Your_Auth_Code_ID
# WORK!!!
45a) ctrl C
to kill the app
46) $ /var/db/boinc/gui_rpc_auth.cfg
set something you can remember as a password instead of the alphanumeric string you found inside
47) $ chmod -R 755 /var/db/boinc/*
48) $ chown -R boinc /var/db/boinc/*
49) $ boinc_client -allow_remote_gui_rpc -attach_project http://setiathome.berkeley.edu @Your_Auth_Code_ID
with this command here the app start, I can connect from a remote machine and see that all was downloaded from setiathome project server. The status of the works downloaded is in "Waiting for shared memory"...
50) /usr/local/etc/rc.d/boinc* start
# 'idprio: RTP_SET: Operation not permitted'

I've never prayed in my life except today

SOME HELP!?

---

in file: /usr/local/etc/rc.d/boinc-client
idprio 31 su - ${boinc_client_user} -c \
"\"${command}\" ${boinc_client_flags} ${command_args}" || return 1

this command is the cause of error 'idprio: RTP_SET: Operation not permitted'

---

$ sysctl security.bsd.unprivileged_idprio=1
-> sysctl: security.bsd.unprivileged_idprio=1: Operation not permitted
;(

---