The only ones you "should" get on a clear qam tuner in WMC should be in this list
: That being said, often a cable company may or may not have other channels available in clear qam but usually don't supply psip data to auto map them in media center. According to your cable company, 2-78 and most of the 400s are also available in clear qam. Anything else may or may not be at any given time since they state a cablecard is required. I'm surprised SiliconDust doesn't have a lineup for Metrocast in your zip, is there a neighboring zip you can try that is a metrocast area? It looks like 06333 may have some of your missing channels under digital cable - not antenna- as the virtual numbers match... 30 for espn Classic, 31 for espn, 32 for espn2 ... 45 for vh1 using 133.1, 131.2, 131.3, 133.4 respectively but your area may use a different map. In theory if someone in your area has a prime, there is a feature that reports back to the lineup server the available clear qam channels to help sd provide a map to the non prime users. I do not know whether or not this is fully implemented by SD but have heard reports and people asking if they can reliably turn off the feature if they have a prime as cablecard tuners don't need the service since they get the map from the cable. Also if you know someone near you with a prime you should be able to get their map.
You are probably going to have to manually map it, prior to me getting a cablecard tuner, I used to have to do this regularly as at one time I had about 25 sd channels that had no psip data. If you think about it 3.1 in your area, according to the list I posted, would be WFSB HD however to appease those using DTAs with older analog sets they probably have a channel 3 available digitally in SD however that usually won't get any psip data as it isn't really channel 3.1.
To map these other clear qam channels, go into media center and enable all unlocked channels, these won't have any guide info yet. Then I go to my tv and press channel up and write down the channel number and the station, occasionally it takes me a while to figure out the station and I find it easier to do at the TV rather than back and forth in media center. Note: the channels in the list will be added using 2.1, 3.1 , 3.2 etc. however they will also show up at the actual channel of (let's say) 69.1, 69.2, 70.4 or whatever the physical channels actually are so there will be a few that the scan picks up that may not show up twice on your TV but will probably show up twice in media center. You will also get a few ppv and on demand that occasionally show up in a scan. There was one cable system I worked with that if a channel wasn't in use (but could be for on demand) it would be free and clear running an advertisement. If you are actually tuning the channels on your tv by keying in "204" for the cooking channel, your TV has to have some type of cablecard, dta, or stb (note: according to your cable company, many of these channels require a cablecard and by them stating this may require one at any time)... in these cases, there may be some diagnostics type menus you can display that shows the physical channel number.
To Manually add the guide listings I then bring up the guide, Right click on the channel, Edit Channel, Edit Listings, and Choose the channel that has the guide data. Personally I would choose Copy, you might get away with combine but I have seen problems when there really isn't another source with the channel… in these cases you may need to use guide tool… Otherwise, it sometimes helps if you can trick media center into thinking you have a STB and ir blaster to at least get the listings for your full lineup as I sometimes don't get the guide data for the other channels unless I do this (perhaps I accidentally chose the analog lineup in these cases, I just know without an ir blaster, it has fought me getting the lineup in the past). Then Click save and move to the next channel.