WL7-equivalent-for-LineExtendYLog

Hello again
I need the equivalence for:
double Y= LineExtendYLog(x1,y1, x2,y2,barra) ; //LOG Scale

I tried WL7 with:

double Y= ExtendLine(x1,y1, x2,y2,barra)

Log Scale Pane and Linear Scale Pane and I always receive "Y"value in linear scale

I have also tried WL7 with something like:
double Y= ExtendLine(x1,y1, x2,y2,barra, true)
but error: ExtendLine only accepts 5 parameters.

Any idea??
Thanks!!