Bios Mods - The Best BIOS Update and Modification Source

Hello !
Need a help. I need to setup DVMT memory amount from default 32mb to
64mb or 96mb or 128mb for installing OSX. Tried setup_var for change variables, but 
got error UEFI message because bios is locked. 
Laptop type is Acer SW5-173, Insyde bios, Setup utility version 5.0
Laptop running last 1.08 bios version, on the Acer site are also couple of older
bios versions available, maybe it's possible use them for modification ?
at least my downgrade with Insyde flash tool not worked.
Probed with Backup Tools bios dump, by the end of process got confirmation 280
that bios is not writeable. Is it any chance to modify the bios at least i can
change the variables ? Of course donation for the help will be acceptable.
Manufaturer bios, for inspection, located here: http://global-download.acer.com/GDFiles/...ER&SC=PA_6
and all 3 bios versions:
http://www.acer.com/ac/en/US/content/sup...t/6247?b=1
if there is at least any chance succeed i can upload original bios dump as well.
Thanks for the support.

Followed moderator advise and tested just in case, that bios is not rsa version. Downloaded Andy's phoenix tool and stock last bios 1.08
Phoenix tool did say nothing about decryption.