[Upgrading, Modifying and Unlocking] jackleung:
I got the P526 phone skin in here http://www.asuspda.net/viewthread.php?tid=26179&page=1 as cab. So I do not have any rgu file for it. Basically, U need the dll and gif file plus the following registry value (U can put it as rgu format if you like)

[HKEY_LOCAL_MACHINE\Software\Microsoft\DialParser]

"DLL-OEM"="\\Windows\\PhoneSkinCrossbow.dll"

"DLL-MS"="tpcutil.dll"

[HKEY_LOCAL_MACHINE\Security\Phone\Skin]

"Ext"="\\Windows\\PhoneSkinCrossbow.dll"

"Enabled"=dword:00000001

[HKEY_LOCAL_MACHINE\Security\Phone\Skin\Dialer]

[HKEY_LOCAL_MACHINE\Security\Phone\Skin\Dialer\landscape]

[HKEY_LOCAL_MACHINE\Security\Phone\Skin\Dialer\landscape\erasebutton]

"bmpTransparency"=dword:FFFFFFFF

"bmpPressed"="\\Windows\\Button_clear_Landscape_down.gif"

"bmpNormal"="\\Windows\\Button_clear_Landscape_normal.gif"

"bmpFlags"=dword:00000000

"bmpDisabled"="\\Windows\\Button_clear_Landscape_disable.gif"

[HKEY_LOCAL_MACHINE\Security\Phone\Skin\Dialer\landscape\other]

"bmpNormal"="\\Windows\\dlrback_land.png"

[HKEY_LOCAL_MACHINE\Security\Phone\Skin\Dialer\landscape\text]

"textDisabledColor"=dword:00484848

"textColor"=dword:00FFFFFF

[HKEY_LOCAL_MACHINE\Security\Phone\Skin\Dialer\landscape\VerbButton]

"bmpTransparency"=dword:FFFFFFFF

"bmpPressed"="\\Windows\\Button_softkey_Landscape_down.gif"

"bmpNormal"="\\Windows\\Button_softkey_Landscape_normal.gif"

"bmpFlags"=dword:00000000

[HKEY_LOCAL_MACHINE\Security\Phone\Skin\Dialer\portrait]

[HKEY_LOCAL_MACHINE\Security\Phone\Skin\Dialer\portrait\erasebutton]

"bmpTransparency"=dword:FFFFFFFF

"bmpPressed"="\\Windows\\Button_clear_Portrait_down.gif"

"bmpNormal"="\\Windows\\Button_clear_Portrait_normal.gif"

"bmpFlags"=dword:00000000

"bmpDisabled"="\\Windows\\Button_clear_Portrait_disable.gif"

[HKEY_LOCAL_MACHINE\Security\Phone\Skin\Dialer\portrait\other]

"bmpNormal"="\\Windows\\dlrback_port.png"

[HKEY_LOCAL_MACHINE\Security\Phone\Skin\Dialer\portrait\text]

"textDisabledColor"=dword:00484848

"textColor"=dword:00FFFFFF

[HKEY_LOCAL_MACHINE\Security\Phone\Skin\Dialer\portrait\VerbButton]

"bmpTransparency"=dword:FFFFFFFF

"bmpPressed"="\\Windows\\Button_softkey_Portrait_down.gif"

"bmpNormal"="\\Windows\\Button_softkey_Portrait_normal.gif"

[HKEY_LOCAL_MACHINE\Security\Phone\Skin\Progress]

[HKEY_LOCAL_MACHINE\Security\Phone\Skin\Progress\landscape]

[HKEY_LOCAL_MACHINE\Security\Phone\Skin\Progress\landscape\other]

"bmpNormal"="\\Windows\\dlrback_land.png"

[HKEY_LOCAL_MACHINE\Security\Phone\Skin\Progress\landscape\TalkEndButton]

"bmpTransparencyTalk"=dword:01000000

"bmpTransparencyEnd"=dword:01000000

"bmpPressedTalk"="\\Windows\\Button_talk_Landscape_down.gif"

"bmpPressedEnd"="\\Windows\\Button_end_Landscape_down.gif"

"bmpNormalTalk"="\\Windows\\Button_talk_Landscape_normal.gif"

"bmpNormalEnd"="\\Windows\\Button_end_Landscape_normal.gif"

"bmpDisabledTalk"="\\Windows\\Button_talk_Landscape_normal.gif"

"bmpDisabledEnd"="\\Windows\\Button_end_Landscape_normal.gif"

[HKEY_LOCAL_MACHINE\Security\Phone\Skin\Progress\landscape\text]

"textDisabledColor"=dword:00484848

"textColor"=dword:00FFFFFF

[HKEY_LOCAL_MACHINE\Security\Phone\Skin\Progress\landscape\VerbButton]

"bmpTransparency"=dword:01000000

"bmpPressed"="\\Windows\\Button_softkey_Landscape_down_01.gif"

"bmpNormal"="\\Windows\\Button_softkey_Landscape_normal_01.gif"

"bmpDisabled"="\\Windows\\Button_softkey_Landscape_normal_01.gif"

[HKEY_LOCAL_MACHINE\Security\Phone\Skin\Progress\portrait]

[HKEY_LOCAL_MACHINE\Security\Phone\Skin\Progress\portrait\other]

"bmpNormal"="\\Windows\\dlrback_port.png"

[HKEY_LOCAL_MACHINE\Security\Phone\Skin\Progress\portrait\TalkEndButton]

"bmpTransparencyTalk"=dword:01000000

"bmpTransparencyEnd"=dword:01000000

"bmpPressedTalk"="\\Windows\\Button_talk_Portrait_down.gif"

"bmpPressedEnd"="\\Windows\\Button_endkey_Portrait_down.gif"

"bmpNormalTalk"="\\Windows\\Button_talk_Portrait_normal.gif"

"bmpNormalEnd"="\\Windows\\Button_endkey_Portrait_normal.gif"

"bmpDisabledTalk"="\\Windows\\Button_talk_Portrait_normal.gif"

"bmpDisabledEnd"="\\Windows\\Button_endkey_Portrait_normal.gif"

[HKEY_LOCAL_MACHINE\Security\Phone\Skin\Progress\portrait\text]

"textDisabledColor"=dword:00484848

"textColor"=dword:00FFFFFF

[HKEY_LOCAL_MACHINE\Security\Phone\Skin\Progress\portrait\VerbButton]

"bmpTransparency"=dword:01000000

"bmpPressed"="\\Windows\\Button_softkey_Portrait_down_01.gif"

"bmpNormal"="\\Windows\\Button_softkey_Portrait_normal_01.gif"

"bmpDisabled"="\\Windows\\Button_softkey_Portrait_normal_01.gif"