There is no supported way to do this. Having said that, you can do it using
louis@Arios:~$ sudo scutil > set Setup:/Network/BackToMyMac > d.add <YYY> <XXX>.members.btmm.icloud.com > set Setup:/Network/BackToMyMac > quit louis@Arios:~$
<YYY> with the UID of the user account on the system (for most people with single account that is 501), and
<XXX> with your iCloud account number. If you don't know that you can check your dns-sd registrations:
louis@Arios:~$ dns-sd -E Looking for recommended registration domains: DATE: ---Wed 22 Aug 2012--- 9:11:04.789 ...STARTING... Timestamp Recommended Registration domain 9:11:04.789 Added (More) local 9:11:04.789 Added icloud.com - > btmm - - > members - - - > <XXX>
The last line will list your iCloud user number. I think they are all 8 digit numbers, at least mine is.