That may work, I cant really say for certain as the lookup ray created is custom coding and is not supported through the form.
looking at your page through Fire Bug, it looks like the price lookup ajax function returns a string separated by a semi colon, see the attached screen shot:
5.60:LWP0038
looks like the first part is the price, and the second part is the item number. after adding that part of the SQL to the query, you would also need to edit the code that creates the Colon separated string to add the remaining inventory.
in the updatePriceDisplay function, the colon sperated string is broken to an array using:
var priceInfo = (silent_form[1]).split(":");
the price is returned through the 0 index of the priceInfo array:
priceInfo[0]
example:
if(priceInfo[0] !="") { document.getElementById("productPrice").innerHTML = "£" + priceInfo[0] + " inc. vat"; }
the item number through the 1 index:
priceInfo[1]
example:
if(priceInfo[1] !="") { document.getElementById("productCode").innerHTML = priceInfo[1]; }
by adding the remaining Invetory to the string, you would reference it using the 2 index:
priceInfo[2]
you could do something like add a hidden form element to the page:
<input type="hidden" name="remaingQuantity" id="remaingQuantity" value="0" />
the add code in the updatePriceDisplay to set the value:
document.getElementById("productCode").value = priceInfo[2];
you also asked this similar question in another thread. In the add to cart button behavior, you can bind the remaining inventory cart column to the remaining inventory hidden element for the calculation that I suggested to work
Where this is custom coding, it is not supported through the forums/
All i can really do is offer suggestions, and examples of the code to use, Note, the examples may need further tweaking, as I can only really give theory here. If you are not able to get this to work on your, you will nee to go through the premiere support service.