you can convert image text as if it were written by hand with a single stroke ?
always following a direction ? tnx

What you want is unclear to me.
What do you mean by "image text" ?

in inkscape, you can trace (=convert as vector) an image that contains text but it won't change the font it was first written with.
You can use filter to add some irregularities to a text and makes it looks more like if it was hand written
You'd better start with a cursive font
http://www.fontspace.com/category/cursive

or scan the trace some text you'd written and process it into inkscape and fontforge

http://fontforge.org/importexample.html

Welcome aboard!

Some info digging:

creating single line fonts
text to single path
shapes to single paths
converting truetype to single line
stroke font
shrinking paths to centerlines

Still I remember there was an even more focused thread on the matter somewhere here.
But as always, tracing the image manually with the pen tool and editing the nodes will give you the best result.