Hi,
There is a cheap solution which works extremely well - a Sphygmomanometer (Blood Pressure Cuff) -
http://www.walgreens.com/store/product.jsp?CATID=100979&navAction=jump&navCount=4&id=prod1557220#
You open it up and can work it between the Seat Cover and the Seat Foam without removing the cover. The bulb can be laid along the side of the console and you can adjust it by operating the valve. Suggest capping off the Pressure Gauge.
At least one Member has done this mod and it works great - for $20, what have you got to lose? You can even get a replacement cuff. Hope this helps...
Happy Motoring!... Jim'99