Can you do this? or is it chicken illegal?

[they'reHISchickens]

Success depends on the hen's personality and hormones. No guarantees but worth a try. Only use young chicks so they imprint on the hen and listen to her. Nothing is worse than a kid that won't listen to mom.

 

[BlazeJester]

I read on a thread here that someone had trouble doing this because she didn't give the broody enough time to set on the eggs and the hen refused the chicks.

The brood cycle is 21 days setting with chicks coming along around day 20 or so. This allows the hen's hormones to cycle completely, rather than trying to force her into the next step before she's ready.

Of course as everyone has mentioned, you're messing with nature here and it may or may not work out. I'd go for letting her sit on the eggs and swapping them out at the appropriate time.