I would like a lisp command that would work like the "extrim" command in autocad. Except I would like it to break at the intersection instead of trimming it. I would like to select my object to be the source of intersection just like the "extrim" command asks you for a pline, line, circle, arc, ellipse, image or text for the cutting edge. please help me. i tried the break touching lisp from xanadu but it doesn't work all the time. I have 2009 map and standard if that matters.

If you need to break lines, polylines, arcs, circles and other entities from your drawing at intersections with other entities, you can make use of the application BreakAll (BreakObjects) or QBRICK.
The LISP application BreakAll (BreakObjects) contains the commands myBreak, BreakAll, BreakwObjects, BreakObject, BreakWith, BreakTouching, BreakSelected. These commands allow to break all or selected objects at points where they are intersected or touched by other objects. The objects are breaked at the intersection points, the appearance of the drawing is not changed.
The LISP application BreakAll can be downloaded from www.xanadu.cz/download, the ARX application QBRICK for AutoCAD version 2000 to 2008 is available here.

i get this message all the time.
; error: bad argument value: AcDbCurve 2128486136
 

I am using Civil 3D 2008 and Standard 2008 I just downloaded it and tried it before sending you the line and it worked great.  Command line: breakall and select the lines you want broken.  

Here is another webiste with lisp programs and you can try this break line lisp:    
 
http://www.cadcorner.ca/lisp.phpmsplcdykee692009-04-08 18:47:49

break all works, but i just want to break the lines at the polyline that i choose for my boundary. i tried using breaktouching, and breakwobject and both error on me.