Connecting Dimension 5150 front-panel mic/phone jacks to audio header on SoundBlaster X-Fi XtremeGamer

First some background so you know the problem and what research I've already done:

I need to get the audio header on my new Sound Blaster X-Fi XtremeGamer card hooked to the front-panel audio jacks of my Dell 5150 desktop.  The problem is that these low-cost X-fi cards use a 1/8 inch "Flexijack" to share the mic input with optical digital output.  This means that if you need to use Flexijack's optical digital out (I do - it's the reason I bought the card), then you lose the ability to connect a mic to the card's rear-panel.  So I need to get a mic input somewhere on this computer and I already prefer to use the front panel connector anyway.

I've read here and elsewhere that many of the Audigy series and the higher-end X-Fi cards have a proprietary header on them, for which Dell did make a cable for my application.  I find these on ebay, but my issue with those is that my XtremeGamer sound card is using the standard Intel HD audio connector/pinout.

So I'm trying to hook that header to my 5150 front-panel connector, which looks similar to the "Audio Cable" connector here:

But, note that the Dell front-panel I/O board pictured above only has headphone out.  So the pinout described there includes no info about where mic input pins might be and in fact is not guaranteed to be correct at all for the 5150.  It is the same connector, though, and pin 7 is missing on mine just like it shows in the picture.

So the first question I have is whether such a cable exists?  Besides the Audigy with its proprietary connector, what sound cards did Dell ship with this product, and did any of these have AC-97 or Intel HD audio headers on them?

Barring the existence of such a cable, the question is whether someone knows the pinout of this 10-pin audio connector that comes off the front I/O panel so I could try to make one...  I have some ideas for trying to reverse engineer the pinout but would likely need some help making the cable from this info.