I don't know if it's possible to do what you're trying to do but you can
make a simple array and assign a move parameter to it so it can be adjusted
manually, not ideal but it'll work.
BTW, what software did you use - this has AEC content and I couldn't even
pick on something without my machine churning away for no apparent reason. I
had to use AECTOACAD to make a usuable file.
Also, there is some good info in these white papers:
http://usa.autodesk.com/adsk/servlet/item?siteID=123112&id=7024848