add on domain question .

i had a hatchel pack and just upgraded to baby for the sole reason of add on domains,

if my domain is : MyDomain , i want 3 of my other domains to redirect to this one. (dont see a problem here , just to put in parked domains)

but my main issue is (why i upgraded) to have another domain : X.com
hosted in HG. when i add it in "addon domain" it does redirect me , but to
X.MyDomain.com .

i want it to show X.com , what do i do ?

thnx for all help.