Enabiling USB on Fanjit's Gta eboot loader? And possible exploit?

Has anyone succesfully being able to access usb mode while running the Gta eboot loader? Its says press triangle but it never works!

Any advice?

Also, if we could go into usb mode without the psp knowing about it (aka through the eboot loader) could we then view the firmware files?

Another thing, if we could access USB mode just before pressing start while updating to 2.7 we could then delete the 2.7 update and replace it with the 1.5 update. could that work?

usb only accesses the memory stick

it wont work, think about the write speed to mem stick
youll delete the 2.7 the update will start(if it is possible to access it in the first place) no update equals empty files written to flash
you just killed your psp
well done