There are plenty of tools available on Arcscripts.  See this [search][1]

I cannot vouch for it, but [Snap and split program][2] looks like it fits your requirements?

Let me know if you have problems "installing" it or using it.


  [1]: http://arcscripts.esri.com/scripts.asp?pg=1&sb=1&ob=asc&eDate=&n=&top=&eLang=&eProd=&perPage=10&eQuery=snap+point+line&Submit2=search
  [2]: http://arcscripts.esri.com/details.asp?dbid=13206