A TkPath question

Hello out there,
I very much like TkPath and am trying to implement some control
widgets based on it. But I stumbled upon a problem: It seems that
there is no TkPath equivalent to the 'arc' command of the regular Tk
canvas. Below is a simplified example from the TkLib's
'controlwidgets' package:
----
package require Tk
package require tkpath

proc mkGUI {parent} {
    set dialcolor lightgreen
    set width   [$c cget -width]
    set xcentre [expr {$width*0.5}]
    set ycentre [expr {$width*1.4}]
    set  t 1.15

    set c [tkp::canvas $parent.c -width 250 -height 150 \
     -background gray50]
    pack $c
    $c create arc \
       [expr {$xcentre-$width*$t}] [expr {$ycentre-$width*$t}] \
       [expr {$xcentre+$width*$t}] [expr {$ycentre+$width*$t}] \
       -start 70.5 -extent 37 -style arc -outline $dialcolor \
       -width [expr {$ycentre*0.245}]

    return $c
}
set c [mkGUI ""]
----
Any ideas how to accomplish the same with TkPath would be highly
appreciated.
Helmut