You'll need to get references to Project and Context objects.
Something roughly like this:
Code:
tell application "Finder" to set file_name to (name of theFile)
set theDate to current date
set theNote to "Scanned " & (theDate as string) & "
"
set projectname to "Proceed Files"
set ContextName to "Some Context"
set theTask to "Proceed: \"" & file_name & "\""
tell application "OmniFocus"
set task_title to theTask
tell default document
set oProj to my GetProject(it, projectname)
set oContext to my GetContext(it, ContextName)
tell oProj
tell (make new task with properties {name:task_title, context:oContext})
set its note to theNote
tell its note to make new file attachment with properties {file name:file_name, embedded:false}
end tell
end tell
end tell
end tell
on GetProject(oDoc, strName)
using terms from application "OmniFocus"
tell oDoc
set lstProj to flattened projects where name = strName
if lstProj ≠ {} then
item 1 of lstProj
else
make new project with properties {name:strName}
end if
end tell
end using terms from
end GetProject
on GetContext(oDoc, strName)
using terms from application "OmniFocus"
tell oDoc
set lstContexts to flattened contexts where name = strName
if lstContexts ≠ {} then
item 1 of lstContexts
else
make new context with properties {name:strName}
end if
end tell
end using terms from
end GetContext