You can buy sleeve pinchers from eBay to suit most engines, you can also use a radiator hose clamp but it will likely oval the sleeve (did to my OS .18) ...

To do the modding yourself just get onto somebody who knows what they are doing, and ask for some details...

Alternatively wade through all the pages of this thread and see some of the stuff people are doing:

http://www.rcuniverse.com/forum/m_52..._1/key_/tm.htm