The attached patch adds canlock support (assuming the library itself gets accepted as net-libs/canlock) to slrn, using the local USE flag "canlock". Using this patch, I have successfully emerged slrn with canlock on my system and tested that it handles cancel locks as it should.
Created attachment 67255 [details, diff] slrn-0.9.8.1.ebuild-canlock.diff
Added to 1.0.0_pre18 in CVS.