JQGrid xmlreader custom id

I need to pass a custom id to the xmlreader structure for the JQGrid to feed off of a combination of nodes in the xml data to uniquely identify the rows.
I currently have this version working
var feedXmlReaderOptions = {
root: "feed",
row: "entry",
repeatitems: false,
id: "d|clmNum,d|seqNum"
};
which concatenates the clmNum and seqNum xml nodes to build an unique identifier for the row.
By the way, the d| refers to a namespace used in the xml, so please ignore it, it's not relevant for this question.
The issue here is that I need a delimiter between the clmNum and seqNum so that I can parse the id later on, during the

ajaxRowOptions: {
beforeSend:...
}
event, so that I can build dynamically the URL that I need to post to. The URL to post to obviously listens to the same id as the grid row, so you see the connection.
What I tried, given the CSS selector style used, were the CSS pseudo elements, through which one can insert custom, non-existent elements, into the selector:
d|clmNum:after { content: "" },d|seqNum
d|clmNum.after(''),d|seqNum
but it's not working...jQuery selectors complain about the {, and the jquery .after(), just like .before(), seem to work inline as methods, not arguments, after the selector returned already a result.
So, anyone has an idea about how to do this?
The alternative with returning the concatenated key during the creation of the xml doesn't work, the xml is not under my control.

Thanks a bunch.
serban@nj,usa

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