Here is the location for some icons that aren't in the PreThemer website. All you do is go to the files section type in the location PLUS icon.png at the end. Make sure the icon is 64x64 as well.

Tweed: (PreThemer has the wrong location, so include both.)
/media/cryptofs/apps/usr/palm/applications/com.pivotallabs.webos.tweed/
/media/cryptofs/apps/usr/palm/applications/com.pivotallabs.tweed.us/

LED Torch:
/media/cryptofs/apps/usr/palm/applications/ca.canucksoftware.ledtorch/

jVault:
/media/cryptofs/apps/usr/palm/applications/com.cohosoft.jvault/

CheckBook (One is App Catalog & the other is Homebrew):
/media/cryptofs/apps/usr/palm/applications/com.glitchtech.checkbook/
/media/cryptofs/apps/usr/palm/applications/com.glitchtechscience.checkbook/

Facebook:
/media/cryptofs/apps/usr/palm/applications/com.palm.app.facebook/

Precorder:
/media/cryptofs/apps/usr/palm/applications/com.palm.net.precoder.fcoaster/

Pixelpipe Uploader (App Catalog Version):
/media/cryptofs/apps/usr/palm/applications/com.pixelpipe.pre/

Friendsbook:
/media/cryptofs/apps/usr/palm/applications/com.sic-software.friendsbook/

My Tether:
/media/cryptofs/apps/usr/palm/applications/net.aonic.my-tether/

Post'er:
/media/cryptofs/apps/usr/palm/applications/net.nizzoli.poster/

Preware (Not sure why it hasn't been changing but here is the location.)
/media/cryptofs/apps/usr/palm/applications/org.webosinternals.preware/