In your SciteUser.properties file (or global):
line.margin.visible = 1

I hope thats the case in older versions of Scite, but head over to
http://scintilla.sourceforge.net/SciTEDoc.html
for more customization info for your properties file

Richard wrote:
> Hi,
>
> I'm running ver. 1.59 and using SciTE primarily for writing Ruby
> scripts.  I'd like to enable line numbers so that I can more easily
> locate lines specified in Ruby diagnostics.
>
> BTW,  do later versions offer any important significant benefits for
> average Ruby programmers?
> 
> TIA,
> Richard