The normalized region for the text is at the outer border of the position. To get it further out, you have to work outside the range of [0 1]. Consider somehting liek this:
function DmnstrBrdrFg
plot3(1:5,1:5,1:5)
set(gca,'XTickLabel',[],'YTickLabel',[],'ZTickLabel',[])
Ps= get(gca,'Position');
OPs= get(gca,'OuterPosition');
set(gcf,'activepositionproperty','outerposition');
PltBrdr(Ps,'P')
PltBrdr2(OPs,'O')
function PltBrdr(Ps,Chr)
FndDtPnts(Ps(1),Ps(2),Chr,1);
FndDtPnts(Ps(1)+Ps(3),Ps(2),Chr,2);
FndDtPnts(Ps(1)+Ps(3),Ps(2)+Ps(4),Chr,3);
FndDtPnts(Ps(1),Ps(2)+Ps(4),Chr,4);
function Out=FndDtPnts(Ps1,Ps2,Chr,Id)
text(Ps1,Ps2,[Chr '_' num2str(Id)],'Unit','normalized','Visible','on');
function PltBrdr2(Ps,Chr)
FndDtPnts(Ps(1)-.1,Ps(2)-.1,Chr,1);
FndDtPnts(Ps(1)+Ps(3)+.1,Ps(2)-.1,Chr,2);
FndDtPnts(Ps(1)+Ps(3)+.1,Ps(2)+Ps(4)+.1,Chr,3);
FndDtPnts(Ps(1)-.1,Ps(2)+Ps(4)+.1,Chr,4);
function Out=FndDtPnts2(Ps1,Ps2,Chr,Id)
text(Ps1,Ps2,[Chr '_' num2str(Id)],'Unit','normalized','Visible','on');
