Hello, I was wondering if someone could help me out with a problem I
have run into. I have a form where I want a list of products  listed
that is generated from an xml file where I pass the element position
to a checkbox value, the user can then check a box of 2-4 products,
click submit and I then want to pass the element positions as a
xsl:parm to the the stylesheet, so it will only show the 2-4 products
the user has selected.

One possiblity is to concatenate the positions, separated by a space
or something, and parse this inside the XSLT. A variety of
techniques for parsing is available form the XSL FAQ.
An alternative solution is to build a DOM tree or something
equivalent, but this depends heavily on the environment and the
XSLT processor itself.