I did the opposite.
I was fermenting a few rounds of cider with WLP300 (Hefe yeast). Then, I mashed in my recipe for a honeywheat Hefe and as it was mashing, I went to the LHBS for the WLP300... and they were out of it!!!
So I siphoned the cider into secondary and added the fruit, and then used the cider's yeast cake for the Honeywheat Hefe.
If you're curious to know how it came out, I can go sneak a sample. It's just about done fermenting. I was going to grab a sample to take a grav reading in the next few days anyway. I think it should be in the clearing phase about now... I can let you know if I can detect any off flavors of cider...
However, you're going the opposite way. And beer has a much stronger taste than cider. And because Hefe yeasts flocculate so darn much, you'll have a hard time pouring out the last remnants of liquid without losing a ton of yeast.
My advice to you is to rack your beer to secondary and let it get a bit dirty. In other words, err on the side of siphoning too much beer. Suck up a bunch of the yeast too. It'll eventually settle out. Maybe you can use finings (gelatin?) if you feel like it for the beer. But this way you'll have the minimum flavor impact on your cider.
Just my $0.02.
Oh and also, the cider needs to bottle condition for about a month to get rid of a funky smell that seems to affect the cider when it's green. At least that's the case with WLP300.