According to Wikipedia, Lt. Col. Blakeslee's regiment had 433 men from Ontario County, New York. Searching at Ancestry.com by regiment (using 'Blakesl*' as a search term in the company field) gives 443 records and yields a record like the one below:
I don't think there is a way to limit this to only have those in a particular company rather than the entire regiment; I don't think that data was extracted in order to be searchable.
I am trying to figure out a fairly easy was to do this using the tools currently at my disposal, as part of my FAN club (family, associates, and neighbors) analysis for the RICHARDSON family.
I already know that the following served in Colonel Tyler's company:
- Asa Davis (son-in-law of Jonathan Richardson II)
- Jonathan Richardson II*
- Joseph Richardson Sr* (died at the Battle of Black Rock)
- Joseph Richardson Jr
- Daniel Richardson*
- Rowland Powell+ (son-in-law of Jonathan Richardson II)
- Calvin Powell+ (son-in-law of Jonathan Richardson II)
- Erastus Lewis (neighbor and deponent for the widow of Joseph Richardson Sr for her bounty land claim)
- Robert Adams** (deponent for the widow of Joseph Richardson Sr for her bounty land claim)
- Eli Stedman/Steadman (acting Ensign for the company during the Battle of Black Rock, and deponent for the widow of Joseph Richardson Sr for her bounty land claim)
* Indicates Richardson brothers
+ Indicates Powell brothers
** No database entry for a Robert Adams in Ancestry.com database.
So I am looking for people who know their ancestor served in this company, as well as ways to uncover this information. I love research!
 Joseph Richardson, "U.S., War of 1812 Service Records, 1812-1813," database entry, Ancestry.com, http://www.ancestry.com : accessed 17 July 2012.