im a little clueless... is there a go bus?

I'm sure theres one.
Last time I got on the wrong bus at union station and traveled all the way to milton. = =
check out the website http://www.gotransit.com/publicroot/....aspx?new=&ps=

Use google maps, with the address in Milton, and McMaster University as your destination. Choose public transit and it'll give you all the info you need. Including GO bus choices .

Nope! Not directly at least. I live in Milton and I commuted last year:
take the 20 southbound from milton GO station (or catch it from the stop at Derry/hwy 25)
get off at the Bronte carpool lot
get on the 47 heading to Hamilton GO, get off at Mac

rinse and repeat...for 8 months.
route 20: http://gotransitnlb.gotransi t.com/...rd/Table20.pdf
route 47: http://gotransitnlb.gotransi t.com/...rd/Table46.pdf

be warned: the bus routes change slightly in off-peak times of the year (ie. exam periods, reading week, Christmas break and summer)

get off at mac? im trying to get to downtown toronto... unless i go from mac to toronto?

I don't know about a bus but there is a GO train that goes Milton to Union station

Bus operates when train doesn't (i.e. non-rush hour).

http://www.gotransit.com/publicroot/...rd/Table21.pdf

Finding the schedule took about 30 seconds. Try it next time.