Hey :]
I'm going to be shadowing the LingCogSci program in 2nd year too. I already took Linguistics 1A03 and 1AA3. You're on the right track with Psych under your belt. The only thing you should do now, is take 2nd year Psych courses that are required as well as the first year Linguistics courses.
http://registrar.mcmaster.ca /calen...nt/pg1450.html
3 units from PSYCH 2E03, 2H03, 2F03, or 2D03.
3 units from PSYCH 2RA3, 2RR3, SOC SCI 2J03
If you are thinking of doing Speech Language Pathology, like I am, they say they recommend taking six units of stats courses. So you can either take Psych stats (2RA3 and 2RR3) or SOC SCI 2J03. However, you need to be in certain programs to be able to take 2J03 - you can always take it in third year instead.
You needn't worry about 2nd year Linguistics courses yet obviously... but I guess to save space for courses in third year, maybe you'll want to do summer courses. Some third year Linguistics courses only require the first year Linguistics courses.
Haha I hope that helps somewhat.
Edit: Oh I forgot. I've talked to a couple people and a TA of mine that's in the program - they reeeeally love it. They even have the Masters program that's new at McMaster this year. They said there's not that many people in the program, so you can make good friends and be on good terms with the professors. Take French! That's a really easy way to get the language requirement. Lol, at least I thought so.
Edit #2: Lol, oh yeah, another requirement pertaining to 2nd year Psych: 6 units from PSYCH 1XX3, 2H03.