diff --git a/glean-core/build/src/lib.rs b/glean-core/build/src/lib.rs
index 451ce1a9ea..dab1a7dde0 100644
--- a/glean-core/build/src/lib.rs
+++ b/glean-core/build/src/lib.rs
@@ -45,6 +45,8 @@ const GLEAN_PARSER_VERSION: &str = "19.0.0";
 pub struct Builder {
     files: Vec<String>,
     out_dir: String,
+    env_dir: Option<PathBuf>,
+    format: String,
 }
 
 impl Default for Builder {
@@ -57,6 +59,8 @@ impl Default for Builder {
         Self {
             files: vec![],
             out_dir,
+            env_dir: None,
+            format: String::from("rust"),
         }
     }
 }
@@ -70,6 +74,8 @@ impl Builder {
         Self {
             files: vec![],
             out_dir: out_dir.into(),
+            env_dir: None,
+            format: String::from("rust"),
         }
     }
 
@@ -81,6 +87,12 @@ impl Builder {
         self
     }
 
+    /// Change output format. Defaults to `rust`.
+    pub fn format<S: Into<String>>(&mut self, format: S) -> &mut Self {
+        self.format = format.into();
+        self
+    }
+
     /// Add multiple definition files, e.g. `metrics.yaml` or `pings.yaml`.
     pub fn files<P>(&mut self, files: P) -> &mut Self
     where
@@ -93,6 +105,15 @@ impl Builder {
         self
     }
 
+    /// Set environment path to use.
+    pub fn env_dir<P>(&mut self, path: P) -> &mut Self
+    where
+        P: Into<PathBuf>,
+    {
+        self.env_dir = Some(path.into());
+        self
+    }
+
     /// Generate the Rust bindings.
     ///
     /// The consumer must include the generated `glean_metrics.rs` file, e.g.:
@@ -111,6 +132,8 @@ impl Builder {
             eprintln!("got env dir: {env_dir}");
             let env_path = PathBuf::from(env_dir);
             VirtualEnv::with_path(&sh, &env_path)?
+        } else if let Some(env_dir) = &self.env_dir {
+            VirtualEnv::with_path(&sh, env_dir)?
         } else {
             let venv = VirtualEnv::new(&sh, "py3-glean_parser")?;
 
@@ -125,7 +148,8 @@ impl Builder {
             println!("cargo:rerun-if-changed={file}");
         }
 
-        let mut args = vec!["translate", "--format", "rust", "--output", out_dir];
+        let mut args = vec!["translate", "--output", out_dir];
+        args.extend(["--format", &self.format]);
         args.extend(self.files.iter().map(|s| s.as_str()));
         venv.run_module("glean_parser", &args)?;