There are apps in App Store: iKeyboard ($9.99), Type2Phone ($9.99), 1Keyboard ($9.99) and Typeeto ($4.99) that allow to use your Mac's keyboard as Bluetooth keyboard. The obvious requirements are Mac with Bluetooth and recent OS X.

Apple has a pretty good record on accessibility features, one of which is the onscreen keyboard. I would be surprised if there is not a way to do enable the extended onscreen keyboard, but I'm still researching where this precise bit of how-to knowledge.

In the meantime, here is Apple's official page for accessibility features related to Physical and Motor Skills (which is the category for the Onscreen Keyboard): http://www.apple.com/accessibility/macosx/physical.html It shows the extended version in their screenshot.

This is overkill (both in features and price), but I felt the need to add the application called "the best on-screen keyboard, not just for the Macintosh, but for any platform." I'm too new to have lots of links. but look at atri.misericordia.edu for a review of KeyStrokes.

Here: have a layout editor, so if you can't see the keys you need in Keyboard Viewer, you can switch them in to replace some keys you don't really care about: http://scripts.sil.org/cms/scripts/page.php?site_id=nrsi&item_id=ukelele

still doing research, will be adding what I find