I have on my s2 biftor 14.
How I can do to install biftor slimkat as second rom?
you can refer to @marjune23 thread about dualboot neatrom 4.1.2/aosp , with @Biftor roms, its same way
the thread :
to dualboot like you want , you need dorimanx kernel (branch 8)
make a backup of your actual system.
you need biftor v14 version modified to dualboot
and when you got it OK with dorimanx kernel branch 8 on 1rst rom,
before all operation i describe here, make an another nandroid backup of your system.
(operation with dorimanx kernel 8.43v119 installed)
1 - take maliv2 patch and extract it on pc
2 - open biftor slimkat rom with winrar
3 - push extracted files from maliv2 patch on same place on biftor slimkat opened zip with winrar (2)
4 - close biftor slimkat modified with winrar
5 - copy biftor slimkat modified on your sd
6 - reboot device to recovery
7 - go to dualboot menu
8 - In dualboot menu, wipe data 2nd rom
9 - In dualboot menu again, go to flash zip from ext/int card menu you know, and choose to flash biftor slimkat modified.
10 - at end of flash, go back and reboot device, push vol down to boot your neww 2nd rom and enjoy.
the most important thing is to have the Biftor v14 modified to dualboot runing fine before to try the 2nd rom managment.
hope i help you.