well the whole cloaking thing is a lil tricky.. i messed with it 3 days now..
1st of all u CANT cloak ALL units with the disabled doodade state..
2nd u will notice starcraft crashes alot while u are messing around with it..
theres also a list of all cloaking methods and which units can be cloaked with which method... all have negative and positive aspects.. i warn ya, this will waste alot of ya time

btw.: heres the link:
http://www.staredit.net/gf/glitcht/scgu.txtin there are all cloaking methods

ADDITION:
another nice way is to place unit 6178.
Its a unit that doesn't visually exist in the game, but acts like an Arbiter.
It casts a cloaking field, form 'nowhere'.
(u will need starforge for it..for the whole cloak thing i suggest it)