This is already possible but you must edit the file it-extrainfo.aspx
there you need to change the label item. for example:
<td align="right" class="lijntje"><strong>Windows Serial: </strong></td>
<td class="lijntje"><input name="Custom1" class="in" type="text" id="Custom1" value="<%# dscustom.FieldValue("Custom1", Container) %>" /></td>
Where now Windows Serial is, was Custom1.
Dont make my mistake to edit the other Custom1 to anything else. these correspond to the database. So editing these makes filling in information usesless because it aint getting saved.
This only work for the looks on the website.