My laptop is quite different of your Dell Mini 9 nice little baby although uses Ricoh Card R/W.
Thanks to this post my PackardBell SB87 SD slot is now working with a 4 GB SDHC card and Xbench reports very close speeds compared to an standard 8GB USB pen.
Just added Dev & Ven ID's into km9 sdhc-v3 kext Info.plist
moved to S/L/Ext, chown, chmod, touch and reboot and it was running fine.
can you please check if i have done things as it must be done?