An app in the Android Market called TAKEphONE has the option to long-press
on a number and have it copied to the clipboard. You might be able to use
this in conjunction with the Button Widget Clicked context in Tasker to do
something like this:

Context: Button Widget Clicked [label: Copy to clipboard]
Task:
If %CLIP ~ +60*
Call 00132%CLIP
Else
Call %CLIP
End If

It's not as straight forward as dialing a number, but it's a way to select
a number and pass that number to Tasker. Once that's done, you can do
anything you want with the number. This would only work with numbers that
are already in your contacts list.