Modify Commit Message Generated From Integrate To Branch

When you right-click on an svn revision in the repository browser and do Integrate with branch the commit message is pre-populated with:
"Merged from trunk" <NEWLINE> <revision commit message> "  [from revision " <revision id> "]"
e.g.
Merged from trunk
HPQC462: fixed the defect as requested  [from revision 232]

Is it possible to change this template?
The only options I can see in the settings are Live Templates and File Templates.