PrintDocument and specific Trays

[PMGuy]

Hi guys:

We're struggling with a peculiar user request.

We're re-implementing an application and a piece of the app allows the
users to print a letter and cooresponding envelope to a designated
printer with the letter being printed from the "Letterhead" tray and
the Envelope printing from the envelop feeder.

The Letterhead tray is NOT the default "LETTER" tray.

We have a routine that loops through the PaperSizes property to try to
specify which tray to use:

private PaperSize GetPaperSize(string sizeName, PrintDocument pDoc)
{
PaperSize res = null;
foreach ( PaperSize pSize in pDoc.PrinterSettings.PaperSizes )
{
if ( sizeName == pSize.PaperName.ToUpper() )
{
res = pSize;
break;
}
}
return res;
}

And this works great for the envelope, because there's only one feeder.
We have tried using a similar routine to loop through PaperSources, but
the only one that comes back is "Form Select" and I'm having the
darnedest time finding any kind of reference for that.

Has anyone else encountered anything like this? Or can you at least
point me in the right direction? We're completely stumped.

TIA.

Matt