Classexec is an amazing *and free* program. This line should do it:
"classExec.exe" "C:\Documents and Settings\ttye\test.xls" --action printto "HP Universal Printing PS" --ifexec
That line will print Excel documents from a command line to a specific printer.
The "HP Universal Printing PS" is the Printer Name.
Download it here:
http://fvue.nl/wiki/ClassExec
