Machine Certificates on Remote Computers z999

I am attempting to set up remote laptop users with the
ability to VPN into my company network via L2TP/IPSec. I
realize that their computers need a machine certificate
issued by a CA (in house) but I don't won't to be forced
into having each laptop join the domain just to request a
machine certificate. I am able to successfully request
and install user certificates via the web enrollment on
the CA. Are there any alternatives for issuing a machine
certificate from a CA to a laptop which is not a member of
the domain?

Thank you.