Did you try one of the examples in the manual?
(The link to the manual with the newest remarks is the link at the left top of this site, called "Online Manual". In your browser you can push Ctrl + F to get the search function where can search for "ent_blend".)
In case that you already tried that, what did you do, and did work and what specifically didn't.
I remember an experience with ent_blend, but don't remember where I used that.
Those examples in the manual are two, one in "ent_blendframe" and one in ent_blendpose".