Take the head off the engine and take the exhaust off the engine. I mean the header part, then move the piston to BDC and take a zip tie and stick it through the exhaust port into the cylinder. Then move the piston up and keep on going up till the sleeve has been pushed up a little. Then move the piston back down and take the zip tie out. Then grab a hold of the sleeve and remove it.

Yes a .15 sleeve will fit in the 2.5 as there the same size engine. A .15=2.5. The .15 is in Cubic Inches and the 2.5 is in CC's. But make sure there from the same type of engine though. Another words dont take a cvr .15 sleeve and stick it in a TRX engine.