It's really pretty easy. Get yourself a spray bottle and fill it with soapy water set the nozzle to spray. Inflate the boat until it is hard but you depress the side with a bit of pressure. Spray the boat all over with the solution in the spray bottle then look for bubbles.
The traditional test is to inflate and leave the boat for 24 hours. Some pressure may be lost but that's ok for an older hypalon boat. try that if you have a secure space like a basement or locked garage.
Places you can take your boat for repair:
i have heard good things about Ken Greeley in Langley 604-514-9975
These guys in White Rock may be worth contacting:
http://www.mutinyinflatables.com/the oldest shop is Kits Inflatables but I had repairs there lately and wasn't thrilled with the cost or that it took 4 weeks after being told it would be a few days. My boat wasn't well handled while it was there either.
there are other place around Greater Vancouver and google will help.
I have both a PVC and hypalon boat and have found hypalon is fairly easy to repair - but you do need time and space. Lot's of info on the web on DIY repairs.
Also look into Kirch's Kwik Patch for the those times you get to the lake or whatever and have an unexpected leak. It can save a day or a whole week.
http://www.patchngo.com/