Hi Red Devil,
The battery boost mod is designed for RFB 2.0 and is unlikely to work properly with RFB 1.4. Sorry I didn't make that clear on the download page.
As far as enabling RFB 1.4 it should take a while to enable in JSGME if it is enabling properly.
I assume there is a different loading page for RFB 1.4, there is for RFB 2.0.
According to this page
http://www.subsim.com/radioroom/showthread.php?t=133091 there should be 2 folders to enable with JSGME, once you have extracted the download.
Having separate installs of SH4 for stock and various mods is not necessary but is convenient.
You can use Multi SH4.
http://silenthunter.filefront.com/file/MultiSH4;110569
Or use something like this
http://www.subsim.com/radioroom/show....php?p=1203456
I hope this helps a bit.