Say you find out the bulk of your apps are in:

/usr/local/apps/

So you have like

/usr/local/apps/breadcrumbz.apk
/usr/local/apps/opera.apk
/usr/local/apps/...

You would just open up the terminal and enter...

~ $ mv /usr/local/apps /sdcard/
~ $ mount --bind /sdcard/apps /usr/local/apps
~ $ echo /sdcard/apps /usr/local/apps bind defaults 0 0 >> /etc/fstab